Process for the preparation of 5-fluoro-1H-pyrazoles starting from hexafluoropropene

ABSTRACT

A new process for the preparation of 5-fluoro-1H-pyrazoles of the general formula (I) as described herein and further reactions with this compound.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a § 371 National State Application of PCT/EP2015/061540, filed May 26, 2015, which claims priority to European Application No. 14169990.0 filed May 27, 2014.

BACKGROUND OF THE INVENTION Field of the Invention

5-fluoro-1H-pyrazoles, in particular 5-Fluoro-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole, are important building blocks for the preparation of crop protection chemicals, as those described in WO 2010051926, WO 2012/069366, WO 2012/0803876 and WO 2012/107343.

Description of Related Art

For the dimerization of hexafluoropropene (HFP) to perfluoro-4-methyl-2-pentene different catalyst and processes have been used.

Perfluoro-2-methyl-2-pentene is commercially available (Fa. Daikin) and P&M Invest (Russia). However, the compound is toxic.

Alternatively, it can be prepared via dimerization of hexafluoropropene (see, e.g., U.S. Pat. No. 5,254,774; R. Haszeldiner et al, Journal of the Chemical Society D: Chemical Communications (1970), (21), 1444-1445.

DE 4228592 describes the preparation of perfluoro-4-methyl-2-pentene in the presence of N,N,N,N-Tetramethylethylendiamin and Kaliumfluoride.

Pazenok et al. describes the preparation of perfluoro-4-methyl-2-pentene in the presence of ammonium and phosphonium perfluorocyclobutane ylides (Pazenok et al., Tetrahedron Letters, (1996), 52(29), 9755-9758).

U.S. Pat. No. 5,254,774 describes the preparation of hexafluoropropene oligomers in the presence of potassium cyanide.

U.S. Pat. No. 2,918,501 describes the preparation of internally unsaturated perfluoroolefins in the presence of fluoride in different solvents like amides, phenylamine or sulfoxides.

For the transformation of perfluoro-4-methyl-2-pentene into perfluoro-2-methyl-2-pentene usually fluorides are used (Brunskill et al, Chem. Com. 1970, 1444).

Also ‘Proton Sponge’ hydrofluoride has been used to generate carbanions from hexafluoropropene (Chambers et al, J. of Fluorine Chemistry (1994), 69(1), 103-108).

U.S. Pat. No. 4,377,717 discloses the production of perfluoro-2-methyl-2-pentene by heating hexafluoropropylene in the presence of activated carbon.

U.S. Pat. No. 4,093,670 (DE 2706603 A1) discloses the production of perfluoro-4-methyl-2-pentene. (E)(CF₃)₂CFCF═CF(CF₃) was isomerized to the more stable perfluoro-2-methyl-2-pentene upon heating for 3 h at 400 in MeCN in the presence of 0.00025 mol each of KF and 18-crown-6 ether. In other examples the 18-crown-6 ether was replaced by benzo-15-crown-5 ether and dibenzo- and dicyclohexyl-18-crown-6 ether.

CN 103483139 discloses a perfluoro-2-methyl-2-pentene preparation method. The method allows perfluoro-2-methyl-2-pentene to be prepared through a catalytic isomerization reaction of a raw material perfluoro-4-methyl-2-pentene.

A method of preparing of perfluoro-2-methyl-2-penten-)3-enolate is described in: V. Snegirev et al Izvestiya Akademii Nauk SSR, Seriya Khimicheskaya (1986), N. 1, pp. 106-119; and T. Martini, J. Fluor. Chem. (1976), 8, 535-540.

It is known that 5-fluoro-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole can be prepared by the treatment of the dimer of hexafluoropropene with water free N,N-dimethylhydrazine in diethyl ether at −50° C. followed by heating of the intermediate at 120° C., Knunyants et al. Izv. Akad. Nauk SSSR (1990) 2583-2589:

However, this two steps transformation requires low temperatures for the first step and results in the formation of CH₃F during the thermal elimination in the second step, making this process expensive, environmentally unfriendly, and particularly difficult for industrialization.

Starting from perfluoro-2-methyl-2-penten and phenylhydrazine, in the presence of triethylamine at −50° C. 1-Phenylpyrazole has been shown to be obtainable in 90% yield (SU 1456419).

Chi et al. J. Fluor. Chem. 98 (1999) 29, reported that the reaction of perfluoro-2-methyl-2-pentene (3) with phenylhydrazine in CH₃CN gave a mixture of isomeric pyrazoles a and b in a ratio 4:1.

Although, commercially available at low cost (especially in the form of their water solutions) the use of monoalkylhydrazines for the regioselective synthesis of the said pyrazoles is not known from the prior art. Moreover, the process is not selective and results in the formulation of three different products (a-c).

Bargamova et al. Div. Chem. Sciences, 39, 2129-32 (1991) describes the preparation of 1-phenyl-3-pentafluoroethyl-4-trifluoroethyl-5-fluoro-pyrazole via reaction of the enolate of hexafluoromethylisopropyl-pentafluoroethyl-ketone with phenylphydrazine in dry monoglyme at −30° C. However, the reaction only gave moderate yields of around 60% and is not suitable for a large scale approach.

Martini et al. J. Flourine Chem., 8, 535-40 (1976) describe the preparation of the enolate of hex-afluoromethylisopropylpentafluoroethyl-ketone starting from perfluoro-2-methyl-2-pentene.

The interaction of the perfluoro-2-methyl-2-pentene (active dimer of hexafluoropropene) with Arylhydrazines leads to the formation of two isomers, albeit 1-pheny-3-perfluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazol is a major one. The mechanism of its formation shown in the schema below. Primary attack of the free NH₂-group on the double bond defines the structure of the regio-isomer. Another situation is during the reaction of perfluoro-2-methyl-2-pentene with N-Alkylhydrazine. Since the N-atom connected with alkyl group is more nucleophilic an interaction of perfluoro-2-methyl-2-pentene with N-Aklyhdrazine should lead to the formation of the wrong isomer.

It has been found that the enolate formed during reaction of the dimer with water easily react with alkyl and arylhydrazinen with selective formation of the desired regiosomer. In this inventive step Alkylhydrazine or Arylhydrazine react with CF₃-group of the enolate producing only one isomer.

The problem to be solved by this invention was to identify a simple and selective process for preparing 5-fluoro-1H-pyrazoles from available fluoroalkenes and mono-substituted hydrazines, which should in particular be amenable for an industrial scale process. As an additional advantage, this process should have a favorable profile with respect to safety and production of unwanted waste material.

SUMMARY

A first aspect of the present invention refers to a process for the synthesis of 5-fluoro-1H-pyrazoles of the general formula (I)

wherein

-   -   R¹ represents optionally halogenated (C₁-C₄)alkyl or optionally         halogenated cyclopropyl, preferably methyl;     -   comprising the steps of     -   preparation of perfluoro-4-methyl-2-pentene (intermediate (2))         in a Step 1

-   -   by reacting hexafluoropropene (compound (1))

-   -   in the presence of a catalyst to form its dimer         perfluoro-4-methyl-2-pentene; and     -   preparation of perfluoro-2-methyl-2-pentene (intermediate (3) in         a Step 2

-   -   by isomerizing perfluoro-4-methyl-2-pentene into         perfluoro-2-methyl-2-pentene; and     -   preparation of perfluoro-2-methyl-2-penten-)3-enolate         (intermediate (4)) in a Step 3

-   -   wherein Cat⁺ refers to a positively charged organic ion,         alkaline metal cation or alkaline earth metal cation by reacting         perfluoro-2-methyl-2-pentene with water and a base; and     -   preparation of compound of formula (I) in a Step 4 by reacting         intermediate (4) in Step 4 with a hydrazine of formula (5)         R¹—NH—NH₂   (5)     -   wherein     -   R¹ is optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl.

A further aspect refers to a process for the preparation of a compound of formula (IV)

in which

-   -   R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   A₁ is C—R²; and     -   R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally         halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy,         optionally halogenated C₁-C₄-alkylsulphonyl, optionally         halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl         (—C(═O)—NH— cyclopropyl); preferably hydrogen, fluorine,         chlorine, bromine, CN, NO₂, methyl, ethyl, fluoromethyl,         difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy,         ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy,         difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy,         trifluoromethoxy, 2,2,2-trifluoroethoxy,         2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl,         methylsulphinyl, trifluoromethylsulphonyl,         trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl, more         preferably hydrogen, fluorine, chlorine, bromine, CN, NO₂,         methyl, fluoromethyl, difluoromethyl, trifluoromethyl,         2,2,2-trifluoroethyl, methoxy, ethoxy, or pentafluoroethoxy,         preferably hydrogen, fluorine, chlorine, bromine, most         preferably chlorine; and     -   A₂ is C—R³ or nitrogen; and     -   R³ is hydrogen, methyl, fluorine or chlorine, preferably         hydrogen; and     -   T represents one of the groups T1-T9 listed below, where the         bond to the pyrazole head group [N₂C₃R¹(C₂F₅)(CF₃)] is marked         with an asterisk *,

and

-   -   R⁶ independently of one another represents halogen, cyano,         nitro, amino or optionally substituted C₁-C₆-alkyl,         C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl,         C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and     -   n represents the values 0-2, preferably 0, provided that n is 0         or 1 in T5, T6 and T8, and provided that n is 0 in T7; and     -   Q is hydrogen, cyano, hydroxy, formyl or one of the groupings         C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl,         C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl,         C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl,         C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl,         aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which         are optionally substituted with one, two, three, four or five,         preferably with one or two, more preferably with one,         substituents independently selected from the group consisting of         hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano,         hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl,         C₄-C₆-cycloalkylcarbamoyl and optionally independently with one,         two or three substituents selected from the group consisting of         halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl,         C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted         phenyl; preferably Q is C₃-C₆-cycloalkyl, or C₃-C₆-cycloalkyl         which is substituted with at least one substituent selected from         the group consisting of chlorine, fluorine, bromine, iodine,         cyano and hydroxy, or C₆-aryl-C₁-C₃-alkyl; more preferably         cyclopropyl, 1-cyano-cyclopropyl or benzyl (—CH₂—C₆H₅);         comprising steps 1, 2, 3 and 4 as described in paragraph [0025].

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

One preferred embodiment refers to the process for the preparation of a compound of formula (IV) as described above, wherein a compound of formula (IV) is a compound of formula (II), preferably of formula (II′) (see, e.g., paragraph [0118]).

Another preferred embodiment refers to the process for the preparation of a compound of formula (IV) described above, wherein a compound of formula (IV) is compound (IIa) (see, e.g., paragraph [0119]):

Another preferred embodiment refers to the process for the preparation of a compound of formula (IV) described above, further comprising the steps of:

-   -   reacting in a Step 5 compound (I) with a cyano-donor to prepare         intermediate of formula (6)

-   -   wherein     -   R¹ is optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   reacting in a Step 6 compound (6) with an inorganic base in a         first hydrolysis step followed by adding an inorganic acid in a         second hydrolysis step to prepare intermediate of formula (7)

-   -   wherein     -   R¹ is optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   reacting in a Step 8 a compound of formula (8) or its salt (8′)         with an activated form (7′) of compound (7)

-   -   wherein R¹, A₁, A₂, and Q are as defined in claim 2 and LG is         any leaving group,         to prepare a compound of formula (II).

Another preferred embodiment refers to the process for the preparation of a compound of formula (IV) described above, wherein a compound of formula (IV) is a compound of formula (III).

Another preferred embodiment refers to the process for the preparation of a compound of formula (III) wherein a compound of formula (III) is a compound of formula III′, preferably compound (IIIa) or compound (IIIb) (see, e.g., paragraphs [0149] to [0151] and [0159]):

Another preferred embodiment refers to the process for the preparation of a compound of formula (III), comprising Steps 1 to 4 as described in claim 1 and further comprising the steps of

-   -   reacting a compound of formula (I) with a compound of         formula (11) by nucleophilic substitution of the fluoride at the         ring position of a compound of formula (I) (herein referred to         as Step 9)

-   -   wherein         -   R¹ is optionally halogenated (C₁-C₄)alkyl or optionally             halogenated cyclopropyl, preferably methyl; and     -   U represents bromine, iodine, triflate, boronic acid, boronic         ester or trifluoroboronate; and     -   the five-membered cycles of E₁-E₃, carbon and nitrogen represent         the 5-membered heterocycles selected from the group consisting         of

-   -   -   wherein         -   R⁶ independently of one another represents halogen, cyano,             nitro, amino or optionally substituted C₁-C₆-alkyl,             C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl,             C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and         -   n represents the values 0-2, preferably 0, provided that n             is 0 or 1 in T5, T6 and T8 and provided n is 0 in T7;

    -   to prepare a compound of formula (12); and

    -   reacting a compound of formula (12) and a compound of         formula (13) (herein referred to as Step 10)

-   -   wherein R¹, A₁, A₂, and Q are as defined for a compound of         formula (III) (or IV, respectively) and U and T are as defined         for compound (11) (and compound (12), respectively); and         -   M represents bromine, iodine or triflate when U represents a             boronic acid, boronic ester or trifluoroboronate; or         -   M represents a boronic acid, boronic ester or             trifluoroboronate when U represents bromine, iodine or             triflate;     -   to prepare a compound of formula (III).

Another preferred embodiment refers to the process for the preparation of a compound of formula (IV) as described above, wherein a compound of formula (IV) is a compound of formula (III″), preferably of formula (III″′) (see, e.g., paragraph [0158]).

Another preferred embodiment refers to the process for the preparation of a compound of formula (III″), preferably of formula (III″′), as described above, characterized by steps 1 to 4 as described above, either optionally further comprising steps 9 and 10 as described above; or optionally further comprising the steps of

-   -   reacting a compound of formula (I) and an azide-donoer to         prepare intermediate (14) (herein referred to as Step 11)

-   -   wherein R¹ is as defined for a compound of formula (III); and     -   reacting intermediate (14) with an intermediate of formula (15)         to give an intermediate (III″*) (herein referred to as Step 12)

-   -   wherein R¹, R⁶, A₁, and A₂ are as defined for compound (III), n         is 0 or 1 and PG is any protective group of the carboxylic group         such as C₁-C₆-alkyl (e.g., methyl).

Another preferred embodiment refers to a process as described above, wherein R¹ is methyl.

Another preferred embodiment refers to a process as described above, wherein the catalyst in Step 1 and the fluoride donor in Step 2 are identical.

Another preferred embodiment refers to a process as described above, wherein the solvent in Step 3 and Step 4 is identical, preferably methylene chloride.

Another preferred embodiment refers to a process as described above, wherein the base in Step 3 is trimethylamine, triethylamine, tripropylamine, tributylamine, DBU, DABCO, N-Ethyldiisopropylamin, N-Butylimidazol, benzyldimethyamine, Pyridin, or Picolin.

Use of hexafluoropropene for the preparation of compound selected from the group consisting of formula (6), (6a), (7), (7a), (I), (Ia), (II), (IIa), (III), (III′), (IIIa), (III″), (III″′), (IIIb), and (IV).

Another aspect refers to a compound of formula (II), preferably of compound (IIa), prepared according to a process comprising Step 1, Step 2, Step 3 and Step 4 as described herein.

Another aspect refers to a compound of formula (III), preferably of compound (IIIa), prepared according to a process comprising Step 1, Step 2, Step 3 and Step 4 as described herein.

Another aspect refers to a compound of formula (III″), preferably compound (IIIb), prepared according to a process comprising Step 1, Step 2, Step 3 and Step 4 as described herein.

Definitions

The term “alkyl” as used herein refers to linear, branched or cyclic saturated hydrocarbyl groups. The definition C₁-C₆-alkyl encompasses the widest range defined herein for an alkyl group. Preferred alkyl are C₁-C₄-alkyl, more preferred C₁-C₃-alkyl, even more preferred C₁-C₂-alkyl. Specifically, this definition encompasses, for example, the meanings of methyl, ethyl, n-, isopropyl, n-, iso-, sec- and t-butyl, n-pentyl, n-hexyl, 1,3-dimethylbutyl and 3,3-dimethylbutyl.

The term “cycloalkyl” as used herein refers to a monocyclic, saturated hydrocarbyl group having 3 to 9 (C₃-C₉-cycloalkyl) and preferably 3 to 6 carbon ring members (C₃-C₆-cycloalkyl), for example (but not limited to) cyclopropyl, cyclopentyl and cyclohexyl. This definition also applies to cycloalkyl as part of a composite substituent, for example cycloalkylalkyl etc., unless defined elsewhere.

The term “halogen” as used herein refers to elements of the 7^(th) main group of the periodic table and their radicals, preferably fluorine, chlorine, bromine and iodine and their radicals. More Preferable halogens are chlorine and fluorine.

The term “optionally halogenated alkyl” or “optionally halogenated cyclopropyl” or other “optionally halogenated” groups or “haloalkyl” or “halocycloalkyl” or similar “halo” groups as used herein refer to alkyl/cycloalkyl/cyclopropyl etc. moieties, wherein at least one (1) hydrogen atom attached to a carbon atom is replaced by a halogen, preferably selected from F, Cl, I, or Br, more preferably selected from F or Cl. Thus, the halogenated form of an alkyl moiety which has n carbon atoms and, thus, 2n+1 hydrogen, may have between 1 and 2n+1 halogen substitutions, i.e. 1, 2, or 3 hydrogen of a methyl moiety are each replaced by a halogen, 1, 2, 3, 4 or 5 hydrogen of an ethyl moiety are each replaced by a halogen, 1, 2, 3, 4, 5, 6 or 7 hydrogen of a propyl moiety are each replaced by a halogen, or 1, 2, 3, 4, 5, 6, 7, 8 or 9 hydrogen of a butyl moiety are each replaced by a halogen. Preferably, all hydrogen of an alkyl moiety are replaced by halogen (perhalogenated moiety). More preferably, all halogen of a perhalogenated moiety are selected from Cl or F or a combination thereof. Even more preferably, all hydrogen of an alkyl moiety are replaced by F. Thus, the halogenated form of a cyclopropyl moiety having 5 hydrogen may have 1, 2, 3, 4 or 5 halogen substitutions, preferably selected from F or Cl or combinations thereof, more preferably the moiety is perfluorinated.

According to the invention, “alkoxy” is straight-chain or branched —O-alkyl, preferably having 1 to 6 or even 1 to 4 carbon atoms, such as, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy. Is also preferably alkoxy groups having 1 to 4 carbon atoms.

According to the invention, “heterocycloalkyl” is a carbocyclic ring system with at least one ring in which at least one carbon atom is replaced by a heteroatom, preferably by a heteroatom from the group consisting of N, O, S, P, B, Si, Se and which is saturated, unsaturated or heteroaromatic where the bonding to the core structure of a compound described herein is localized on a ring atom. Unless defined otherwise, the heterocyclic ring comprises preferably 3 to 9 ring atoms, in particular 3 to 6 ring atoms, whereof 1 to 5 ringatoms are carbon atoms provided that one or more, preferably 1 to 4, in particular 1, 2 or 3, ringatoms are heteroatoms in the heterocyclic ring. Preferably, a heteroringatom is selected from the group consisting of N, O and S, where, however, two oxygen atoms should not be directly adjacent. The heterocyclic rings usually comprise not more than 4 nitrogen atoms, and/or not more than 2 oxygen atoms and/or not more than 2 sulphur atoms. If the heterocyclyl radical or the heterocyclic ring is optionally substituted, it can be fused with other carbocyclic or heterocyclic rings. In the case of optionally substituted heterocyclyl, the invention also encompasses polycyclic systems such as, for example, 8-azabicyclo[3.2.1]octanyl or 1-azabicyclo[2.2.1]heptyl. In the case of optionally substituted heterocyclyl, the invention also encompasses spirocyclic systems, such as, for example, 1-oxa-5-azaspiro[2.3]hexyl.

According to the invention, “alkylcycloalkyl” is mono-, bi- or tricyclic cycloalkyl group which is substituted by one or more alkyl group(s), preferably wherein the sum of carbonatoms in the cycloalkyl and alkyl part of the substituent is between 4 to 15 or 4 to 9 carbon atoms, such as, for example, ethylcyclopropyl, isopropylcyclobutyl, 3-methylcyclopentyl and 4-methylcyclohexyl. Is also preferably alkyl-cycloalkyls having 4, 5 or 7 carbon atoms, such as, inter alia, ethylcyclopropyl or 4-methylcyclohexyl. Preferably, the alkylpart of an alkylcyclyoalkyl substituent is C₁ or a C₂ alkyl (—CH₃ or —C₂H₅).

According to the invention, “cycloalkylalkyl” is an alkyl group which is substituted by one or more mono-, bi- or tricyclic cycloalkyl group(s), preferably wherein the sum of carbonatoms in the cycloalkyl and alkyl part of the substituent is between 4 to 15, more preferably between 4 to 9 carbon atoms, such as, for example, cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl and cyclopentylethyl. Is also preferably cycloalkylalkyls having 4, 5 or 7 carbon atoms such as, inter alia, cyclopropylmethyl or cyclobutylmethyl. Preferably, the alkylpart of a cyclyoalkylalkyl substituent is C₁ or a C₂ alkylene (—CH₂— or —C₂H₄—).

According to the invention, “aryl” is an aromatic hydrocarbyl group (aryl). Preferably, an aryl group refers to C₆-C₁₄-aryl, i.e. an aryl group having between 6 and 14 carbon ring atoms. Also according to the invention “heteroaryl” refers to an aromatic group comprising at least one heteroatom ring atom individually selected from the group consisting of O, N, P and S (e.g., 1, 2, 3, 4 or even more heteroatom ring atom(s) although heteroaryl with 1, 2, 3 or 4 heteroatom ring atom are preferred). The definition C₅-C₁₄-heteroaryl refers to an aryl group comprising at least one heteroatom ring atom individually selected from the group consisting of O, N, P and S while the sum of ring atoms, including the at least one heteroatom ring atom as defined above, is between 5 and 14. For example, the term C₅-heteroaryl includes furane (1 oxygen ring atom and 4 carbon ring atoms) or imidazole (2 nitrogen ring atoms and 3 carbon ring atoms). More preferred aryl compounds are C₆-aryl, C₅-heteroaryl or C₆-heteroaryl. Examples are phenyl, cycloheptatrienyl, cyclooctatetraenyl, naphthyl and anthracenyl; 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyrrolyl, 3-pyrrolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl, 1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,2,4-thiadiazol-3-yl, 1,2,4-thiadiazol-5-yl, 1,2,4-triazol-3-yl, 1,3,4-oxadiazol-2-yl, 1,3,4-thiadiazol-2-yl and 1,3,4-triazol-2-yl; 1-pyrrolyl, 1-pyrazolyl, 1,2,4-triazol-1-yl, 1-imidazolyl, 1,2,3-triazol-1-yl, 1,3,4-triazol-1-yl; 3-pyridazinyl, 4-pyridazinyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl.

According to the invention, “Arylalkyl” and “heteroarylalkyl” is an alkyl group (alkylene chain) which is substituted by one or more aryl group(s) or one or more heteroaryl group(s), respectively. The alkylene chain has preferably between 1 and 6 carbon atoms (C₁-C₆-alkylene chain), preferably between 1 and 3 carbon atoms. The definition C₇-C₂₀-arylalkyl group encompasses the widest range defined herein for an arylalkyl group having a total of 7 to 20 atoms in the combination of aryl ring system and the alkylene chain. Preferred arylalkyls are C₇-C₉-arylalkyl, e.g., C₆-aryl-C₁-C₃-alkyl such as benzyl (—CH₂—C₆H₅), phenylethyl (—CH₂—CH₂—C₆H₅) or phenylpropyl (—(CH₂)₃—C₆H₅). The definition C₆₋₂₀-heteroarylalkyl group encompasses the widest range defined herein for an heteroarylalkyl group having a total of 6 to 20 atoms in the combination of heteroaryl ring system and the alkylene chain, wherein at least 1 ring atom in the heteroaryl ring system is a heteroatom. Preferred heteroarylalkyls are C₆-C₉-arylalkyl, e.g., C₅-heteroaryl-C₁-C₃-alkyl such as pyrrol-2-yl-methyl (—CH₂—C₄NH₄) or C₆-heteroaryl-C₁-C₃-alkyl such as 2-pyridin-2-yl-methyl (—CH₂—C₅NH₄).

According to the invention, “Alkylaryl” is an aryl group which is substituted by one or more alkyl group(s), preferably C₁-C₆-alkyl group(s), more preferably C₁-C₃-alkyl group(s). The definition C₇-C₂₀-alkylaryl group encompasses the widest range defined herein for an alkylaryl having a total of 7 to 20 atoms in the aryl ring system and alkyl group(s), preferably C₇-C₉-alkylaryl, such as C₁-C₃-alkyl-C₆-aryl. Specifically, this definition encompasses, for example, the meanings of tolyl (—C₆H₄—CH₃), ethylphenyl (—C₆H₄—C₂H₅), or 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dimethylphenyl.

Similarly, an “alkylheteroaryl” group is a heteroaryl group as defined herein which is substituted by one or more alkyl group(s). The definition C₆-C₂₀-alkylheteroaryl group encompasses the widest range defined herein for an alkylheteroaryl having a total of 6 to 20 atoms in the heteroaryl ring system and alkyl group(s), which individually are preferably C₁-C₆-alkyl group(s), more preferably C₁-C₃-alkyl group(s). Preferably alkylheteroalkyl is C₆-C₉-alkylheteroaryl. For example, C₁-C₃-alkyl-C₆-heteroaryl, such as 2-methyl-pyridyl (—C₅NH₃—CH₃), 2-ethyl-pyridyl, 2,3-dimethyl-pyridyl or 2-methyl-3-ethyl-pyridyl.

According to the invention, “alkylcarbonyl” is a straight-chain or branched alkyl-C(═O), preferably having 2 to 7 carbon atoms (—C(═O)—C₁-C₆-alkyl), such as methylcarbonyl, ethylcarbonyl, n-propylcarbonyl, isopropylcarbonyl, sec-butylcarbonyl and tert-butylcarbonyl. Preferable alkylcarbonyls have 1 to 4 carbon atoms (C₁-C₃-alkyl-C(═O)).

According to the invention, “alkylaldehyde” is a straight-chain or branched alkyl substituted with a C(═O)H group (-alkyl-CH(═O)), preferably having 2 to 7 carbon atoms (—C₁-C₆-alkyl-CH(═O)). Preferable alkylcarbonyls have 2 to 4 carbon atoms (—C₁-C₃-alkyl-CH(═O)).

According to the invention, “aminoalkyl”, “alkylaminoalkyl” (secondary amine) and “aminocarbonylalkyl”, respectively, refer to amino (—NH₂), aminoalkyl (—NHalkyl) and (—C(═O)—NH₂), respectively, substituted alkylene chains. Preferably, alkyl in the three listed amino substituents is C₁-C₆-alkyl, more preferably C₁-C₄-alkyl, e.g., C₁-alkylamino refers to —CH₂—NH₂, C₁-alkylamino-C₁-alkyl refers to —CH₂—NH—CH₃, and C-alkylcarbonylamino refers to —CH₂—C(═O)—NH₂.

“Optionally substituted” groups as used herein are preferably substituted by 1, 2, 3, 4, 5, preferably by 1 or 2 independently selected from the group consisting of hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano, hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl, C₄-C₆-cycloalkylcarbamoyl and phenyl.

The person skilled in the art is aware that the terms “a” or “an”, as used in the present application, may, depending on the situation, mean “one (1)” “one (1) or more” or “at least one (1)”.

Not included herein are chemical structures and combinations of embodiments which are against natural laws and which the person skilled in the art would therefore exclude based on his/her expert knowledge. Ring structures having three or more adjacent oxygen atoms, for example, are excluded.

“Intermediate” as used herein describes the substances which occur in the process according to the invention and are prepared for further chemical processing and are consumed or used therein in order to be converted to another substance. The intermediates can often be isolated and intermediately stored or are used without prior isolation in the subsequent reaction step. The term “intermediate” also encompasses the generally unstable and short-lived intermediates which occur transiently in multistage reactions (staged reactions) and to which local minima in the energy profile of the reaction can be assigned.

The inventive compounds may be present as mixtures of any different isomeric forms possible, especially of stereoisomers, for example E and Z isomers, threo and erythro isomers, and optical isomers, but if appropriate also of tautomers. Both the E and the Z isomers are disclosed and claimed, as are the threo and erythro isomers, and also the optical isomers, any mixtures of these isomers, and also the possible tautomeric forms.

DETAILED DESCRIPTION

In the following, the invention and various embodiments of the invention are described in more detail. It is obvious to the person skilled in the art that all embodiments can be present alone or in combination.

Surprisingly, 5-fluoro-1H-pyrazoles of the general formula (I)

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl, preferably methyl, can be prepared in high purity and in a short and simple process by reacting in step 1 Hexafluoropropen (1) to perfluoro-4-methyl-2-pentene (intermediate (2)), in step 2; isomerization of (2) to perfluoro-2-methyl-2-pentene (intermediate (3)), in step 3; reaction of (3) with water and a base to intermediate (4) followed by reaction of (4) with hydrazines of formula (5) (step 4) resulting in compounds of formula (I):

wherein R¹ represents hydrogen, optionally halogenated (C₁-C₄)alkyl or optionally halogenated cyclopropyl, preferably methyl. The terms “base” and “Cat⁺” are as defined in paragraphs [0083] to [0088].

Step 1: Dimerisation of Hexafluoropropen

Typically, the reaction is carried out in the presence of a catalyst such as a fluoride (F⁻) donor (e.g., Me₄N F, Bu₄N F, NaF, KHF₂, KF or CsF. Preferred catalysts are KHF₂, KF and CsF, more preferably KF or CsF.

Typical solvents are polar solvents like Glyme (glycolethers such as monoglycolether of formula C₁-C₄-alkylOCH₂CH₂OH or benzylOCH₂CH₂OH or phenylOCH₂CH₂OH, dialkylether of formula C₁-C₄-alkylOCH₂CH₂O—C₁-C₄-alkyl or esters C₁-C₄-alkylOCH₂CH₂OCOCH₃, preferably dimethoxyethane), acetonitrile, DMF (dimethylformamide), DMA (dimethylacetamide),N-methylpyrrolidone, sulfolane, benzonitrile, dimethoxyethan, diethyleglkykoldimethylether. Reaction temperature is between 10° C. and 50° C., preferably between 20° C. and 40° C.

Reaction time is depending of the reaction size and is typically between 1 min and 30 h.

Although purification steps for Dimer (2) and/or removal or exchange of solvent after Step 1 can occur before Step 2, Step 1 and Step 2 can be performed as a one pot reaction.

A “one pot reaction”, as long as not stated otherwise, refers to two reaction steps (e.g. Step 3 and Step 4) which are carried out without interim purifying steps after the first reaction step and prior of performing the second step and/or without the need of exchanging solvent.

“Without purifying steps” as used in the present application refers to the absence of purifying steps selected from the group consisting of removal of more than 10% of the solvent of a reaction mixture by evaporation, e.g. under reduced pressure and/or heating, crystallization of an intermediate or compound resulting from a reaction step in a solvent different from the solvent of the reaction mixture, or chromatography.

“Exchanging solvent” as used in the present application means that no major amounts of a solvent of a different kind is added to a reaction mixture. “No major amount” refers to a volume of less than 50 vol % based on the volume of a solvent in a reaction mixture. For example, the addition of 5 ml acetonitrile to a reaction mixture comprising 200 ml methylene chloride is not an exchange of solvent even if part of the solvent of the reaction mixture, such as 50 vol % of the solvent of a reaction mixture, was removed by, e.g. phase separation. However, the addition of more than 100 ml of acetonitrile (solvent of a different kind) to a reaction mixture comprising 200 ml methylene chloride as solvent is considered an exchange of solvent even if methylene chloride is not removed prior to the addition of acetonitrile. Also considered as an exchange of solvent is the removal of at least 95 vol % of a first solvent (e.g. acetonitrile) in a reaction mixture after the first reaction step by, e.g., phase separation, followed by adding a solvent of a different kind, e.g., dichloromethane.

Although it is not mandatory, a one pot reaction is preferably carried out in the same reaction vessel.

Step 2: Isomerization of perfluoro-4-methyl-2-pentene (inactive Dimer) to perfluoro-2-methyl-2-pentene

Typically, the isomerization is carried out in the presence of a fluoride donor.

NaF, KF, KHF₂, AlF₃ or Cs F can be used in combination with an auxiliary catalyst comprises one or more of ethylenglykoldimethylether, sulfolane, 15-crown ether-5 and 18-crown ether-6, quaternary ammonium salts like (tetraalkylammonium fluorides, hydrodifluorides (e.g. alkaline hydrodifluorides such as KHF₂) hydrochloride or hydrobromide) or tetra-C₁-C₆-alkylphosphonium salts or tetraphenylphosphonium salts like Ph₄P Cl, Ph₄P Br, Ph₄P Br or Ph₄P HF₂.

Preferred fluoride donors are NaF, KF, KHF₂, CsF, AlF₃ more preferable KF.

Isomerization usually occurs at elevated temperature between 25 to 60° C. at normal pressure, but the reaction can be performed under pressure up to 6 bar and a temperature between 60 to 80° C.

Typically solvents are polar solvents like glyme, acetonitrile, DMF, DMA, benzonitrile, dimethoxyethane or diethylenglkykoldimethylether or combinations thereof. More preferable solvents are acetonitrile, DMF or DMA.

The reaction time is usually between 1 h and 10 h such as between 2 h and 8 h.

In one preferred embodiment, the solvent in Step 1 and Step 2 is the same, preferably acetonitrile.

In another preferred embodiment, Step 3 and Step 4 are reacted as a one-pot-reaction and the solvent in Step 3 and Step 4 is the same, preferably acetonitrile or methylene chloride, more preferably methylene chloride.

Although purification steps for intermediate (3) and/or exchange of solvent after Step 2 can occur before Step 3; Step 1 to Step 3; or Step 2 and Step 3 can be performed as a one pot reaction, i.e. without purifying steps for intermediate (2) and/or intermediate (3) prior of performing Step 3 and/or without the need of exchanging solvent prior of performing Step 2 and Step 3 or prior of performing Step 3, respectively.

Step 3: Reaction of perfluoro-2-methyl-2-pentene (3) with Water and a Base

wherein Base and Cat⁺ are as defined below.

Surprisingly, is has been found that the interaction of fluoroalkenes of formula (3) in a first step with water, and a base, followed by a reaction of the formed intermediates of formula (4) with hydrazines of formula (7) proceeds regioselectively with the formation of only or almost only one isomeric pyrazole of the formula (I) in a high yield.

The reaction is performed in the presence of an organic and/or inorganic base. An organic base as used herein is an organic molecule which is able to bind at least one proton resulting in a positively charged organic ion (cation). For example, an organic molecule such as triethylamine is able to bind one (1) proton resulting in an (organic molecule H)⁺ ion, or an inorganic alkaline metal or alkaline earth metal salt wherein the alkaline or alkaline earth metal, respectively, is present in form of its cation in the reaction mixture.

The term “Cat⁺” as used herein refers to a positively charged ion (cation) under the proviso that the cation is not a single proton, preferably a positively charged organic ion (organic moleculeH)⁺), e.g. a protonated organic base, or an alkaline metal ion or an alkaline earth metal ion. A Cat⁺ refers either to a one-time positively charged molecule or, e.g., in case of an alkaline earth metal ion, to a two-times positively charged molecule. Preferably, a Cat⁺ is a one-time positively charged molecule such as an alkaline metal ion, (HN(methyl)₃)⁺, (HN(ethyl)₃)⁺, or H(N(propyl)₃)⁺.

Typical organic bases (organic molecule) used in Step 3 are trimethylamine, triethylamine, tripropylamine, tributylamin, methydiisopropylamin, N-methylmorpholine, pyridine, alkylpyridines, trimethylbenzylammonium hydroxide, tetrabutylalammonim hydroxide, Hünig base (N-ethyldiisopropylamin, DBU (1,8-Diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4-diazabicyclo[2.2.2]octane), N-butylimidazol, benzyldimethyamine.

A preferred organic base is trimethylamine, triethylamine, tripropylamine, tributylamine, DBU, DABCO, N-Ethyldiisopropylamin, N-Butylimidazol, benzyldimethyamine, Pyridin, or Picolin. Especially preferred are trimethylamine, triethylamine.

Typical inorganic bases to carry out the reaction are alkaline metal hydroxides, halogenides, carbonates or hydrogencarbonates, alkaline earth metal hydroxides, carbonates or hydrogencarbonates, such as NaHCO₃, K₂CO₃, NaOH, NaHCO₃, KF, CsOH, LiOH, Cs₂CO₃. Preferred inorganic bases are K₂CO₃, NaHCO₃, KF, Cs₂CO₃.

Typically, Cat⁺ depends on the choice of the base used in the reaction. Preferably, Cat⁺ is selected from Li⁺, Na⁺, K⁺, Cs⁺, (NAlkyl₄)⁺, (HNAlkyl₃)⁺. Most preferable, Kat is (HNAlkyl₃). In connection with (N(Alkyl)₄)⁺ or (HN(Alkyl)₃)⁺ wherein the term alkyl in the terms (NAlkyl₄)+, (HNAlkyl₃)⁺ refers to (C₁-C₂₀)alkyl, preferably to (C₁-C₁₀)alkyl, more preferably to (C₁-C₅)alkyl such as N(methyl)₃, N(ethyl)₃, or N(propyl)₃.

Preferred compounds of formula (4) are compounds (4a) and (4b):

Typical solvents for carrying out step 3 are alkanes, like hexanes e.g. cyclohexane or methylcyclohexane; haloalkanes, e.g., dichlorometane or dichlorethane; and polar solvents like glyme, acetonitrile, DMF, DMA, Benzonitrile, Dimethoxyethan, Diethyleglkykoldimethylether. Preferred solvents are dichlorethane and acetonitrile

According to a further preferred embodiment of the present invention, the amount of water used in the reaction is in the range of 1 to 10 equivalents, preferably in the range of 1 to 7 equivalents, more preferably between 1 to 5 equivalents per one equivalent of compound of formula (3).

The amount of base is in the range of 1 to 7 equivalents, preferably between 1.5 to 7 equivalents, more preferably between 1.5 to 5 equivalents per one equivalent of the compound of formula (3).

Preferably, the ratio of base to water is 1:1 or the base is even present in excess compared to the amount of water such as 1.5:1 or 2:1 up to 7:1 or preferably up to 5:1.

Reaction temperature is between −10 and 30° C. The reaction time is not critical und depends on scale size and usually between 0.5 and 2 h. Reaction is exothermic.

Generally, the reaction time for the performance of Step 3 is not of critical importance and can inter alia depend on the reaction volume, nature of the base employed. Preferably it is within the range of 0.5 h to 5 h, more preferably within the range of 1 h to 3 h.

Although purification steps for intermediate (4) and/or removal or exchange of solvent after Step 3 can occur before Step 4, Step 1 to Step 4 or Step 2 to Step 4 or Step 3 and Step 4 can be performed as a one pot reaction, i.e. without purifying steps for Dimer (2) and/or intermediate (3) and/or intermediate (4) prior of performing Step 4 and/or without the need of removing or exchanging solvent prior of performing Step 4.

Step 4: Reaction of Compounds of Formula (4) with Hydrazines of Formula (5)

wherein R¹ is selected from hydrogen, optionally halogenated (C₁-C₄)-alkyl, e.g., optionally halogenated methyl ethyl, n-propyl, i-propyl, 1-butyl, 2-butyl, 2-methyl-prop-1-yl, or 2-methyl-prop-2-yl, or optionally halogenated cyclopropyl, preferably R¹ is methyl.

For the performance of the invention that compound (4) preferably exist under conditions that prevent its isomerization or decomposition, for instance by formation of the corresponding ketone, via e.g. acidification. This is typically ensured by the control of the pH or the choice of a proper base to stabilize the compounds of formula (4). Preferably, the pH is between 5 and 12, more preferably between 6 and 11 even more preferably, the pH is 7 or higher such as 8 or higher, most preferably between 7 and 10 or between 8 and 10.

The ratio of the compound of formula (4) and the compound of formula (5) can vary within a large range, preferably it is within 0.9 to 3.5 equivalents, more preferably between 1 to 2.5 equivalents, even more preferably between 1 to 1.5 equivalent of (5) per one equivalent of the compound of formula (4).

According to a further embodiment of the present invention, the cyclization is performed at temperatures ranging from −5° C. to 50° C., more preferably at temperatures ranging from 0° C. to 30° C., most preferably from 0° C. to room temperature, e.g. from 0° C. to around 20° C. such as from 0° C. to 17° C. or from 0° C. to 23° C.

The cyclisation reaction (step 4) can be performed in different solvents selected from

-   -   alkanes, like hexanes e.g. cyclohexane or methylcyclohexane;     -   haloalkanes, preferably dichlorometane, dichlorethane;     -   alcohols, preferably methanol, ethanol, or isopropanol;     -   nitriles, preferably acetonitrile, or butyronitrile;     -   amides, preferably dimethylformamide, or dimethylacetamide;     -   ethers like diethylether, methyltert.butylether,         dimethoxyethane, diglym,     -   benzene, toluene, dichlorobenzene, chlorobenzene.

Particularly preferred solvents for the cyclisation are dichloromethane, dichloroethane, acetonitrile and butyronitrile, most preferred solvents for this reaction are dichloromethane, acetonitrile and butyronitrile.

Generally, the reaction time is not of critical importance and can depend on the reaction volume, preferably, it is within the range of 3 h to 20 h, more preferably within the range of 1 h to 5 h.

A particularly preferred embodiment of the present invention relates to a process for preparing compound of formula (Ia), starting from hexafluoropropen

wherein the hydrazine of formula (5) is (CH₃)NHNH₂.

Step 5

In a Step 5, the compound of formula (I), preferably compound (la), can be transformed into its CN analog of formula (6) or (6a), respectively

wherein R¹ is hydrogen, optionally halogenated (C₁-C₄)alkyl or optionally halogenated cyclopropyl, preferably methyl; and preferably, a compound of formula (6) is a compound of formula (6a):

by reacting compound (I), preferably compound (la), with a CN-donor such as alkaline cyanides (e.g., NaCN, KCN, CsCN, or CuCN).

Typical solvents are acetonitrile, DMF, DMA, N-methylpyrrolidone (NMP), Sulfolan, dimethoxyethane, diglym. Preferred solvents are acetonitrile, DMF or DMA.

Typically, the temperature for this reaction is between 30° C. and 120° C., preferably between 40° C. and 110° C., more preferably above 60° C. such as between 60° C. and 120° C. or between 60° C. and 100° C.

Generally, the reaction time is not of critical importance and can depend on the reaction volume. Preferably, the reaction time is between 2 h and 8 h, more preferably between 4 and 8 h.

Step 6

In a Step 6, a compound of formula (6), preferably (6a), can be transformed in its carboxylic acid analog of formula (7), preferably formula (7a), respectively, according to hydrolysis steps known in the art:

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl, preferably methyl; preferably, a compound of formula (7) is a compound of formula (7a):

The conversion of a cyano group (—CN) into a carboxylic group (—COOH) is generally performed under acidic or basic conditions.

For acidic hydrolysis, preference is given to mineral acids, for example H₂SO₄, HCl, HSO₃Cl, HF, HBr, HI, H₃PO₄ or organic acids, for example CF₃COOH, p-toluenesulphonic acid, methanesulphonic acid, trifluoromethanesulphonic acid. The reaction can be accelerated by the addition of catalysts, for example FeCl₃, AlCl₃, BF₃, SbCl₃, NaH₂PO₄. The reaction can likewise be performed without addition of acid, only in water.

Basic hydrolysis is effected in the presence of inorganic bases such as alkali metal hydroxides, for example lithium hydroxide, sodium hydroxide or potassium hydroxide, alkali metal carbonates, for example Na₂CO₃, K₂CO₃ and alkali metal acetates, for example NaOAc, KOAc, LiOAc, and alkali metal alkoxides, for example NaOMe, NaOEt, NaOt-Bu, KOt-Bu of organic bases such as trialkylamines, alkylpyridines, phosphazenes and 1,8-diazabicyclo[5.4.0]undecene (DBU). Preference is given to the inorganic bases, for example NaOH, KOH, Na₂CO₃ or K₂CO₃. To generate the protonated acidic form of formula (7) or (7a), respectively, a following step of acidification should follow.

Typically, suitable inorganic acids for performing the acidification after completion of the basic hydrolysis is any acid which is stronger than the deprotonated form of a compound of formula (7) or (7a), respectively. Preference is given to mineral acids, for example H₂SO₄, HCl, HF, HBr, HI, H₃PO₄ or organic acids, for example CF₃COOH, p-toluenesulphonic acid, methanesulphonic acid, trifluoromethanesulphonic acid. Preferred acids for this acidifications are HCl or H₂SO₄.

The reaction step can be performed in substance or in a solvent. Preference is given to performing the reaction in a solvent. Suitable solvents are, for example, selected from the group comprising water, alcohols such as methanol, ethanol, isopropanol or butanol, aliphatic and aromatic hydrocarbons, for example n-hexane, benzene or toluene, which may be substituted by fluorine and chlorine atoms, such as methylene chloride, dichloroethane, chlorobenzene or dichlorobenzene; ethers, for example diethyl ether, diphenyl ether, methyl tert-butyl ether, isopropyl ethyl ether, dioxane, diglyme, dimethylglycol, dimethoxyethane (DME) or THF; nitriles such as methyl nitrile, butyl nitrile or phenyl nitrile; amides we dimethylformamide (DMF) or N-methylpyrrolidone or mixtures of such solvents, particular preference being given to water, acetonitrile, dichloromethane and alcohols (ethanol). Preferably, the reaction is carried out in water. The process step of the invention is generally performed under standard pressure. Alternatively, however, it is also possible to work under vacuum or under elevated pressure (for example reaction in an autoclave with aqueous HCl).

The reaction time may, according to the batch size and the temperature, be selected within a range between 1 hour and several hours such as between 1 h and 30 h, preferably between 3 h and 20 h.

Preference is given to conversion by means of basic hydrolysis followed by an acidification.

The process step of the invention is performed preferably within a temperature range from 20° C. to 150° C., more preferably at temperatures of 30° C. to 110° C., most preferably at 30° C. to 80° C.

Generally the reaction time may, according to the batch size and the temperature, be selected within a range between 1 hour and several hours such as between 1 h and 30 h, preferably between 3 h and 20 h.

Compounds of Formula (II)

The present invention also refers to a process to produce an insecticidal compound of formula (II), preferably of formula (II′), more preferably of formula (IIa), e.g., known from WO 2010/051926

wherein

-   -   R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   A₁ is C—R²; and     -   R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally         halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy,         optionally halogenated C₁-C₄-alkylsulphonyl, optionally         halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl         (—C(═O)—NH-cyclopropyl); preferably hydrogen, fluorine,         chlorine, bromine, CN, NO₂, methyl, ethyl, fluoromethyl,         difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy,         ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy,         difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy,         trifluoromethoxy, 2,2,2-trifluoroethoxy,         2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl,         methylsulphinyl, trifluoromethylsulphonyl,         trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl, more         preferably hydrogen, fluorine, chlorine, bromine, CN, NO₂,         methyl, fluoromethyl, difluoromethyl, trifluoromethyl,         2,2,2-trifluoroethyl, methoxy, ethoxy, or pentafluoroethoxy,         preferably hydrogen, fluorine, chlorine, bromine, most         preferably chlorine; and     -   A₂ is C—R³ or nitrogen; and     -   R³ is hydrogen, methyl, fluorine or chlorine, preferably         hydrogen; and     -   Q is hydrogen, cyano, hydroxy, formyl or one of the groupings         C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl,         C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl,         C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl,         C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl,         aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which         are optionally substituted with one, two, three, four or five,         preferably with one or two, more preferably with one,         substituents independently selected from the group consisting of         hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano,         hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl,         C₄-C₆-cycloalkylcarbamoyl and optionally independently with one,         two or three substituents selected from the group consisting of         halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl,         C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted         phenyl; preferably Q is C₃-C₆-cycloalkyl, or C₃-C₆-cycloalkyl         which is substituted with at least one substituent selected from         the group consisting of chlorine, fluorine, bromine, iodine,         cyano and hydroxy, or C₆-aryl-C₁-C₃-alkyl; more preferably         cyclopropyl, 1-cyano-cyclopropyl or benzyl (—CH₂—C₆H₅);     -   preferably, a compound of formula (II) is a compound of formula         (II′):

wherein A¹ and A² and Q are as defined for a compound of formula (II).

In one preferred embodiment, the compound of formula (II) is compound (Ia) defined by the following substituents:

R¹ A₂ A₁ Q CH₃ C—H C—Cl Benzyl

The new and inventive process for preparing a compound of formula (II), preferably (II′), more preferably (IIa), is characterized by steps 1 to 4 described in paragraphs [0063] to [0103], optionally by additional Step 5 and Step 6 described in paragraphs [0104] to [0117] optionally, by the subsequent step Step 8 described below. Optionally, compound (8) in Step 8 can be produced by the reaction indicated in Step 7 which is described below:

Wherein R¹ and A₁ and A₂ and Q have the meanings described for compounds of formula (II). LG is any desired leaving group, e.g. halogen or anhydrate.

Typically, an amine derivative of the formula (8) does not only refer to the amine but also to its salt form (8) H⁺ W⁻ wherein W⁻ is selected from ⁻, Cl⁻, Br⁻, J⁻, HSO₄ ⁻, CH₃COO⁻, BF₄ ⁻, CH₃SO₃ ⁻, Toluensulphonic acid, CF₃COO⁻ or CF₃SO₃ ⁻.

wherein W⁻ is selected from ⁻, Cl⁻, Br⁻, J⁻, HSO₄ ⁻, CH₃COO⁻, BF₄ ⁻, CH₃SO₃ ⁻, Toluensulphonic acid, CF₃COO⁻ or CF₃SO₃ ⁻.

Thus, one preferred embodiment refers to the reaction of Step 8 wherein the compound of formula (8) is present in its salt form (8) H⁺ W⁻, wherein W⁻ is selected from ⁻, Cl⁻, Br⁻, J⁻, HSO₄ ⁻, CH₃COO⁻, BF₄ ⁻, CH₃SO₃ ⁻, Toluensulphonic acid, CF₃COO⁻ or CF₃SO₃ ⁻.

In one more preferred embodiment, a compound of formula (8) is compound (8a) and/or its salt (8a′):

wherein

-   -   W⁻ (in the case of compound (8a′)) is selected from the group         consisting of F⁻, Cl⁻, Br⁻, J⁻, HSO₄ ⁻, CH₃COO⁻, BF₄ ⁻, CH₃SO₃         ⁻, Toluensulphonic acid⁻, CF₃COO⁻ or CF₃SO₃ ⁻.

Step 8

In Step 8, compounds according to the invention of the type (II), preferably (II′), more preferably (IIa), can be synthesized by reacting amines of the general structure (8) (or their salts) with intermediate (7′) which is an activated form of carboxylic acid derivative of formula (7), preferably of formula (7a). The reaction can be carried out with or without solvents. In this step, a suitable base can likewise be used.

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl, preferably methyl.

An activated form of carboxylic acid derivative of formula 7, preferably formula (7a), which is indicated in the reaction scheme of Step 8 above by having any leaving group LG in the —C(═O)LG group, encompasses a) analogs of formula (7) or (7a), respectively, wherein the OH of the COOH group is replaced by a suitable leaving group such as halogen; b) anhydrates of compounds of formula (7) or (7a), respectively; or c) compounds of formula (7) or (7a), respectively in the presence of a coupling reagent which presence activates the compound of formula (7) or (7a), respectively, in the sense of the present invention, such as dicyclohexylcarbodiimide or 1-hydroxybenzotriazole. The skilled person is aware of suitable leaving groups preparation of anhydrates of a carboxylic acid or suitable coupling reagents for acid/amine reactions and the preparation of such compounds. Preferred leaving groups are carboxylic acid halides such as carboxylic acid chlorides or fluorides.

Cyclic carboxylic acid halides, as inter alia represented by the general structure (7′), can be prepared simply by reacting a heterocyclic carboxylic acid of compound (7) with halogenating reagents such as thionyl chloride, thionyl bromide, phosphoryl chloride, oxalyl chloride, phosphorus trichloride, etc. (Houben-Weyl (1952) vol. VIII, p. 463 ff.).

Amines derivatives of the formula (7) and their salts are known in the art, commercially available or can be prepared in a known manner (see, e.g., WO 2010/051926).

The synthesis of carboxamides represented by the formula (II), preferably (II′), more preferably (IIa), can, however, also be carried out using coupling reagents such as dicyclohexylcarbodiimide and additives such as 1-hydroxybenzotriazole (König et al. Chem. Ber. (1970), 788-798). It is also possible to use coupling reagents such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, 1,1′-carbonyl-1H-imidazole and similar compounds.

Coupling reagents which are used for carrying out the synthesis process are all those which are suitable for the preparation of an ester or amide bond (cf. e.g. Bodansky et al., Peptide Synthesis, 2nd ed., Wiley & Sons, New York, 1976; Gross, Meienhofer, The Peptide: Analysis, Synthesis, Biology (Academic Press, New York, 1979).

Furthermore, mixed anhydrides can also be used for the synthesis of (II), preferably (II′), more preferably (IIa) (see, e.g., Anderson et al, J. Am. Chem. Soc (1967), 5012-5017). In this process it is possible to use various chloroformates, such as, for example, isobutyl chloroformate, isopropyl chloroformate. Similarly, diethylacetyl chloride, trimethylacetyl chloride and the like can be used for this.

In general, Step 8 can be carried out optionally/if appropriate, in the presence of a suitable diluent/solvent and, optionally/if appropriate, in the presence of suitable basic reaction auxiliary.

The process according to the invention can be performed in the presence of a diluent/solvent. Useful diluents for this purpose include all inert organic solvents, preferably aliphatic, alicyclic or aromatic hydrocarbons, for example petroleum ether, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene or decalin; halogenated hydrocarbons, for example chlorobenzene, dichlorobenzene, dichloromethane, chloroform, tetrachloromethane, dichloroethane or trichloroethane; ethers such as diethyl ether, diisopropyl ether, methyl t-butyl ether, methyl t-amyl ether, dioxane, tetrahydrofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane or anisole; ketones such as acetone, butanone, methyl isobutyl ketone or cyclohexanone; nitriles such as acetonitrile, propionitrile, n- or i-butyronitrile or benzonitrile; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformanilide, N-methylpyrrolidone or hexamethylphosphoramide, more preferably are used chlorobenzene and toluene.

Preferred diluents are aliphatic, alicyclic or aromatic hydrocarbons, for example petroleum ether, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene or decalin; and halogenated hydrocarbons, for example chlorobenzene, dichlorobenzene, dichloromethane, chloroform, tetrachloromethane, dichloroethane or trichloroethane; e.g. toluene or chlorbenzene.

The solvent which may be used is any solvent which does not adversely affect the reaction, such as, for example, water. Of suitability are aromatic hydrocarbons such as benzene or toluene; halogenated hydrocarbons such as dichloromethane, chloroform or tetrachloromethane, open-chain or cyclic ethers such as diethyl ether, dioxane, tetrahydrofuran or 1,2-dimethoxyethane; esters such as ethyl acetate and butyl acetate; ketones such as, for example, acetone, methyl isobutyl ketone and cyclohexanone; amides such as dimethylformamide and dimethylacetamide; nitriles such as acetonitrile; and other inert solvents such as 1,3-dimethyl-2-imidazolidinone; the solvents can be used alone or in combination of two or more.

The base (basic reaction auxiliary) used can be an acid acceptor such as an organic base such as triethylamine, ethyldiisopropylamine, tri-n-butylamine, pyridine and 4-dimethylaminopyridine; furthermore, the following bases can, for example, be used: alkali metal hydroxides, such as, for example, sodium hydroxide and potassium hydroxide; carbonates such as sodium hydrogencarbonate and potassium carbonate; phosphates such as dipotassium hydrogenphosphate and disodium phosphate; alkali metal hydrides, such as sodium hydride; alkali metal alcoholates, such as sodium methanolate and sodium ethanolate. These bases can be used in ratios of from 0.01 to 5.0 mole equivalents based on (8) and (7′). Furthermore, silver(I) cyanide can also be used as base and activator (see, e.g., Journal of Organic Chemistry. 1992, 57, 4394-4400; Journal of Medicina Chemistry 1992, 35, 3905-3918; Journal of Organic Chemistry 2003, 68, 1843-1851).

However, in one preferred embodiment of the present invention, step 8 is carried out in the absence of an acid acceptor and the leaving group is Cl or F, more preferably Cl.

In the context of the invention, “in the absence of an acid acceptor” means in the absence of an acid acceptor other than the amine reactant (8) or, in other words, “in the absence of an additional acid acceptor wherein “additional” means in addition to the amine derivative of the formula (8) (or its salts (8′) which is part of the reaction. An “additional acid acceptor” in the sense of the present invention can be a base in addition to the amine compound according to the invention or compounds which reduce the strength of a formed acid such as salts, e.g. silvercyanide (AgCN), which are able to transform strong acids which are formed during the reaction (leaving group anion plus hydrogen cation) into insoluble salts and weak acids (e.g. formed HCl (if the leaving group is chlorine) reacts with AgCN to insoluble AgCl and weak base HCN).

Surprisingly, the carboxamides of the formula (II) can be prepared in the absence of an acid acceptor with good yields in high purity and selectivity. A further advantage of the process according to the invention is that the workup is simpler, since an acid acceptor is not needed. This causes fewer or no waste water, an easier purification process without prior isolation by addition of an aliphatic alcohol in the same reaction vessel, and the process can be run in a higher concentration. The resulting product has then been obtained with a surprising purity superior to 90% or even close to 100%, and with less reagent and effort, while prior conditions in presence of an acid acceptor generally leads to a purity close to less than 90% The process according to the invention becomes more economically viable.

Thus, one preferred embodiment refers to a reaction for the production of compounds of formula (IIa)

-   -   wherein leaving group LG refers to F, Cl, Br or I, preferably F         or Cl, and         in the absence of an acid acceptor in addition to compound (8a).

The suitable reaction temperature is in the range from −20° C. up to the boiling point of the particular solvent. In general, the reaction temperature is between 70° C. to 150° C., preferably between 80° C. to 140° C., e.g. 100° C. or around 100° C. such as 80° C. to 130° C. or 80° C. to 120° C.

The reaction time is between 1 min and 96 h depending on the choice of volume, reactants, solvents and reaction temperature.

For the process of Step 8, generally between 0.8 and 1.5 mol, preferably 0.8 to 1.4 mol, 0.9 to 1.4 mol, equimolar amounts or 1 to 1.2 mol of amine derivative of the formula (8) or its salt, preferably (8a) or (8a′), are used per mole of the pyrazole-carboxamide derivatives (7′).

One preferred embodiment refers to a reaction of a compound (8a) or its salt (8a′), respectively, with compound (7′), wherein X is Cl and wherein the ratio of compound (8a) (or its salt (8a′)) and (7′) wherein X is Cl is between 1:1 or 1:1.3, preferably between 1:1 to 1:2 such as between 1:1 to 1:1 or even 1:1.

Depending on the choice of volume, reactants, solvents and reaction temperature, the reaction time can vary between one minute and 96 h. Typically, the reaction time is up to 15 hours, but the reaction can also be terminated even earlier in the case of complete conversion. Preference is given to reaction times of 5-10 hours.

The reaction of Step 8 is generally performed under standard pressure. However, it is possible to work under elevated or reduced pressure—generally between 0.1 bar and 10 bar It is preferable to work under reduced pressure to remove HCl from the reaction volume.

The reaction of Step 8 can generally be performed under atmosphere. However, it is preferred to carry out the process under protective gas such as argon, or nitrogen.

Moreover the skilled person will understand that it is also possible to react a compound of formula (7′) with a compound of formula (8*), wherein the —C(═O)—NH-Q moiety of compounds of formula (8) is replaced by a C(═O)—OH or C(═O)—PG moiety in a compound of formula (8*), wherein PG stands for any protective group of a carboxylic group (e.g. a methylesther, i.e. PG represents —O-methyl). The deprotection of the carboxylic moiety of the resulting compound (II*) of a reaction with a compound (8*) and/or activating of the carboxylic moiety and/coupling with an amine to arrive at a compound of formula (II) are well known to a skilled person. Compounds of the general structure (II*) can be synthesized by reacting an amine of the general structure (7) with activated carboxylic acid derivatives of the general structure (8*). In this connection, the same conditions apply for the choice of solvent, the reaction conditions, the reaction time and the reagents as for the synthesis of (II), described above.

Step 7

Compounds of the general structure (8) can be synthesized by reacting an amine of the general structure (10) with activated carboxylic acid derivatives of the general structure (9). In this connection, the same conditions apply for the choice of solvent, the reaction conditions, the reaction time and the reagents as for the synthesis of (II), preferably (II′), more preferably (IIa), described in step 8 above.

Compounds of Formula (III)

The present invention also refers to a process to produce an insecticidal compound of formula (III) or (III′)

in which

-   -   R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   A₁ is C—R²;     -   R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally         halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy,         optionally halogenated C₁-C₄-alkylsulphonyl, optionally         halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl         (—C(═O)—NH-cyclopropyl); preferably hydrogen, fluorine,         chlorine, bromine, CN, NO₂, methyl, ethyl, fluoromethyl,         difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy,         ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy,         difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy,         trifluoromethoxy, 2,2,2-trifluoroethoxy,         2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl,         methylsulphinyl, trifluoromethylsulphonyl,         trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl, more         preferably hydrogen, fluorine, chlorine, bromine, CN, NO₂,         methyl, fluoromethyl, difluoromethyl, trifluoromethyl,         2,2,2-trifluoroethyl, methoxy, ethoxy, or pentafluoroethoxy,         preferably hydrogen, fluorine, chlorine, bromine, most         preferably chlorine; and     -   A₂ is C—R³ or nitrogen;     -   R³ is hydrogen, methyl, fluorine or chlorine, preferably         hydrogen; and     -   Q is hydrogen, cyano, hydroxy, formyl or one of the groupings         C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl,         C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl,         C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl,         C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl,         aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which         are optionally substituted with one, two, three, four or five,         preferably with one or two, more preferably with one,         substituents independently selected from the group consisting of         hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano,         hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl,         C₄-C₆-cycloalkylcarbamoyl and optionally independently with one,         two or three substituents selected from the group consisting of         halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl,         C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted         phenyl; preferably Q is C₃-C₆-cycloalkyl, or C₃-C₆-cycloalkyl         which is substituted with at least one substituent selected from         the group consisting of chlorine, fluorine, bromine, iodine,         cyano and hydroxy, or C₆-aryl-C₁-C₃-alkyl; more preferably         cyclopropyl, 1-cyano-cyclopropyl or benzyl (—CH₂—C₆H₅);     -   T represents one of the 5-membered heteroaromatics T1-T8 listed         below, where the bond to the pyrazole head group is marked with         an asterisk *,

wherein

-   -   R⁶ independently of one another represents halogen, cyano,         nitro, amino or optionally substituted C₁-C₆-alkyl,         C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl,         C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and     -   n represents the values 0-2, preferably 0, provided that n is 0         or 1 in T5, T6 and T8 and provided n is 0 in T7;     -   preferably, a compound of formula (III) is a compound of formula         (III′)

wherein A₁ and A₂ and T and Q have the meanings described above for a compound of formula (III).

For clarity sake, if n in any formula described herein is 0 (zero), carbon ring atoms with a free valence are then substituted by hydrogen.

In one preferred embodiment, the compound of formula (III) is compound (IIIa) defined by the following substituents:

R¹ T n R⁶ A¹ A² Q CH₃ T3 0 — C—Cl C—H 1-cyanocyclopropyl  

The new and inventive process for preparing a compound of formula (II), preferably (III′), more preferably (IIIa), is characterized by the steps 1 to 4 described in paragraphs [0063] to [0103], optionally by subsequent Step 9 and Step 10:

The radicals A₁, A₂, R¹ and Q have the meanings described for compound (III). Preferably, R¹ is methyl. The five-membered cycles of E₁-E₃, carbon and nitrogen represent the 5-membered heterocycles defined under T. U represents bromine, iodine or triflate if M represents a boronic acid, boronic ester or trifluoroboronate. U represents a boronic acid, boronic ester or trifluoroboronate if M represents bromine, iodine or triflate.

Step 9

The compounds of the general structure (12) can be prepared by processes known from the literature by, e.g., nucleophilic substitution of F at the aromatic ring (WO2007-107470; Sakya et al., Tetrahedron Letters 2003, 44, 7629-7632) from the appropriate starting materials (I), preferably (Ia), and (11).

Step 10

Compounds of formula (III) or (III′), preferably compound (IIIa), can be prepared by using palladium-catalysed reactions with the reaction partners (12) and (13) (see, e.g., WO 2005/040110 or WO 2009/089508). The compounds of the general structure (13) are either commercially available or can be prepared by processes known to the person skilled in the art.

Moreover, the skilled person is aware that it is alternatively possible to react a compound of formula (12) with a compound of formula (13*), wherein the —C(═O)—NH-Q moiety of compounds of formula (13) is replaced by a C(═O)—OH or C(═O)—PG moiety in a compound of formula (13*), wherein PG stands for any protective group of a carboxylic group (e.g. an alkylesther such as methylesther, i.e. PG represents —O-methyl). The deprotection of the carboxylic moiety of the resulting compound (III*) of a reaction with a compound (13*) and/or activating of the carboxylic moiety and/coupling with an amine to arrive at a compound of formula (III) are well known to a skilled person.

In sum, compounds of the general structure (III) can be synthesized by reacting an amine of the general structure (10) with activated carboxylic acid derivatives of the general structure (III*). In this connection, the same conditions apply for the choice of solvent, the reaction conditions, the reaction time and the reagents as for the synthesis of (II), described in step 8 above.

Compounds of Formula (III″)

In another preferred embodiment, the invention refers to a process to prepare a compound of formula (III″), preferably of formula (III′″), e.g., known from WO 2012/107434:

wherein R¹, R⁶, n, A₁, A₂, and Q are as defined for compound (III), preferably; preferably, a compound of formula (III″) is a compound of formula (III″′)

wherein R⁶, n, A₁, A₂ and Q are as defined for a compound of formula (III), preferably, wherein n is 0.

In one preferred embodiment, the compound of formula (III′″) is compound (IIIb) defined by the following substituents:

n R⁶ A¹ A² Q 0 — C—Cl C—H 1-cyanocyclopropyl

The process for preparing a compound of formula (III″), preferably (III″′), more preferably (IIIb), is characterized by the steps 1 to 4 described in paragraphs [0063] to [0103], optionally by subsequent Step 9 and Step 10 as described in paragraphs [0154] to [0157] or optionally by subsequent Step 11 and Step 12. Steps 11 and 12 are known in the art (see, e.g., WO 2012/107434).

Step 11

In a step 11, a compound of formula (I), preferably of formula (Ia), can be transformed into its azido analog of formula (14) or (14a), respectively:

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl, preferably methyl, preferably, a compound of formula (14) is compound (14a)

by reacting compound (I), preferably compound (la), with an azide-donor such an alkaline metal azide (e.g., NaN₃).

Preferably, the reaction is carried out in a polar aprotic solvent such as tetrahydrofuran (THF), ethyl acetate (EtOAc), acetone, dimethylformamide (DMF), acetobitrile or dimethyl sulfoxide (DMSO). One preferred solvent is DMSO.

Typically, the reaction temperature is between 0° C. and 60° C., preferably between 10° C. and 30° C., more preferably between 20° C. and 30° C.

The reaction time can inter alia depend on the reaction volume and is usually between 0.5 h to 30 h.

Step 12

In a step 12, an intermediate of formula (14), preferably of formula (14a), is reacted with an intermediate of formula (15) to give an intermediate of formula (III″*) or preferably a compound of formula (III′″*) wherein R¹ is methyl, respectively:

wherein R¹, R⁶, A₁, and A₂ are as defined for compound (III), n is 0 or 1 and PG is any protective group of the carboxylic group such as C₁-C₆-alkyl (e.g., methyl). Preferably, R¹ in a compound of formula (III″*) is methyl (compound of formula (III″′*)). More preferably, R¹ in formula (III″*) is methyl and n in formula (III″*) is 0.

Compounds of formula (15) are commercially available or can be prepared according to methods known in the art.

Typically, the solvent for reaction of Step 12 is a polar protic solvent such as water, formic, n-butanol, isopropanol, nitromethane, ethanol, methanol, acetic acid or combinations thereof. Preferably, the solvent is n-butanol, isopropanol, ethanol, water or combinations thereof.

The reaction is carried out in the presence of copper or a copper catalyst such as copper sulfate or copper (I) iodide, optionally in the presence of a base such as N-ethyldiisopropylamine. However, also other organic bases are suitable. In case of a Cu(II) catalyst, a reducing agent such as sodium ascorbate may be used. In case of Cu(0) catalyst, such as an amine salt, an oxidizing agent may be used (see, e.g., Angewandte Chemie, International Edition (2009), 48(27), 4900-4908 and cited references, Lutz., Angew. Chem. Int. Ed. 2008, 47, 2182-2184 and cited references, and Bock et al., Eur. J. Org. Chem. (2006), 51-68 and cited references).

Starting from a compound of formula (III″*), compounds of formula (III), (III′), (III″), (III″′), (IIIb), (III″″), (IV) or (IV′) can be easily prepared according to methods known in the art (see, e.g. WO 2012/107434).

Step 13

Compound of formula (III″″) may be prepared by reaction of a compound of formula (III″*) wherein O-PG is C₁-C₆-alkoxy via hydrolysis. For instance, in the case wherein —O-PG is methoxy or ethoxy, the hydrolysis can be done with water and a base, such as potassium hydroxide or lithium hydroxide, in the absence or in the presence of a solvent, such as, for instance, tetrahydrofurane or methanol. In the case where R is, for example, tert-butoxy, the hydrolysis is done in the presence of acid, such as trifluoroacetic acid or hydrochloric acid. The reaction is carried out at a temperature of from −120° C. to 130° C., preferably from −100° C. to 100° C.

wherein R¹, R⁶, n, A₁, and A₂ are as defined for compound (III), preferably R¹ is methyl and n is 0.

Compounds of the general structure (III) can be synthesized by reacting an amine of the general structure (10) with activated carboxylic acid derivatives of the general structure (III″″). In this connection, the same conditions apply for the choice of solvent, the reaction conditions, the reaction time and the reagents as for the synthesis of (II) described in step 8 above.

Compounds of Formula (IV)

One aspect of the present invention refers to a process for the preparation of a compound of formula (IV), preferably of formula (IV′):

in which

-   -   R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally         halogenated cyclopropyl, preferably methyl; and     -   A₁ is C—R²; and     -   R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally         halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy,         optionally halogenated C₁-C₄-alkylsulphonyl, optionally         halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl         (—C(═O)—NH-cyclopropyl); preferably hydrogen, fluorine,         chlorine, bromine, CN, NO₂, methyl, ethyl, fluoromethyl,         difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy,         ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy,         difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy,         trifluoromethoxy, 2,2,2-trifluoroethoxy,         2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl,         methylsulphinyl, trifluoromethylsulphonyl,         trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl, more         preferably hydrogen, fluorine, chlorine, bromine, CN, NO₂,         methyl, fluoromethyl, difluoromethyl, trifluoromethyl,         2,2,2-trifluoroethyl, methoxy, ethoxy, or pentafluoroethoxy,         preferably hydrogen, fluorine, chlorine, bromine, most         preferably chlorine; and     -   A₂ is C—R³ or nitrogen; and     -   R³ is hydrogen, methyl, fluorine or chlorine, preferably         hydrogen; and     -   T represents one of the 5-membered heteroaromatics T1-T9 listed         below, where the bond to the pyrazole head group is marked with         an asterisk *,

and

R⁶ independently of one another represents halogen, cyano, nitro, amino or optionally substituted C₁-C₆-alkyl, C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl, C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and

-   -   n represents the values 0-2, preferably 0, provided that n is 0         or 1 in T5, T6 and T8 and provided n is 0 in T7.     -   Q is hydrogen, cyano, hydroxy, formyl or one of the groupings         C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl,         C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl,         C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl,         C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl,         aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which         are optionally substituted with one, two, three, four or five,         preferably with one or two, more preferably with one,         substituents independently selected from the group consisting of         hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano,         hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl,         C₄-C₆-cycloalkylcarbamoyl and optionally independently with one,         two or three substituents selected from the group consisting of         halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl,         C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted         phenyl; preferably Q is C₃-C₆-cycloalkyl, or C₃-C₆-cycloalkyl         which is substituted with at least one substituent selected from         the group consisting of chlorine, fluorine, bromine, iodine,         cyano and hydroxy, or C₆-aryl-C₁-C₃-alkyl; more preferably         cyclopropyl, 1-cyano-cyclopropyl or benzyl (—CH₂—C₆H₅);     -   preferably, a compound of formula (IV) is a compound of formula         (IV′):

wherein T, A₁, A₂ and Q are as defined for a compound of formula (IV), preferably wherein T is selected from T3, T8 or T9. comprising the steps of

-   -   reacting in a first step hexafluoropropene (1)

-   -   in the presence of a catalyst to form its dimer         perfluoro-4-methyl-2-pentene (2)

-   -   isomerization of (2) in a second step to         perfluoro-2-methyl-2-pentene (3)

-   -   reacting in a third step (3) with water and a base to         intermediate (4),

-   -   wherein Cat⁺ refers to a positively charged organic ion, an         alkaline metal cation or an alkaline earth metal cation;     -   reacting in a fourth step compound of formula (4) with a         hydrazine of the formula (5)         R¹—NH—NH₂  (5),     -   wherein     -   R¹ is optionally halogenated (C₁-C₄)alkyl or optionally         halogenated cyclopropyl, preferably methyl to prepare compound         of formula (I)

One preferred embodiment refers to a process for the preparation of compound (IV) where R¹—in all formulae disclosed herein wherein R¹ is present—represents methyl.

Another preferred embodiment refers to a process for the preparation of compound (IV) where n—in all formulae disclosed herein wherein n is present—represents 0.

Another preferred embodiment refers to a process for the preparation of compound (IV) where A₂—in all formulae disclosed herein wherein A₂ is present—represents C—R², wherein R² represents hydrogen, fluorine, chlorine or bromine, most preferably wherein R² represents chlorine.

Another preferred embodiment refers to a process for the preparation of compound (IV) where A₂—in all formulae disclosed herein wherein A₂ is present—represents C—R³ wherein R³ represents hydrogen.

Another preferred embodiment refers to a process for the preparation of compound (IV) where T—in formula (IV) and all further formulae disclosed herein wherein T is present—represents T3, T8 or T9.

Another preferred embodiment refers to a process for the preparation of compound IV where Q—in all formulae disclosed herein wherein Q is present—represents optionally with cyano substituted C₃-C₆-cycloalkyl or C₆-aryl-C₁-C₃-alkyl even more preferred Q represents optionally with cyano substituted C₃-cycloalkyl or benzyl, even more preferred, Q represents with cyano substituted cyclopropyl (e.g., 1-cyano-cyclopropyl) or benzyl.

Another preferred embodiment refers to a process for the preparation of compound (IV) where R¹—in all formulae disclosed herein wherein R¹ is present—represents methyl and n—in all formulae disclosed herein wherein n is present—represents 0 and A₁—in all formulae disclosed herein wherein A₁ is present—represents C—Cl and A₂—in all formulae disclosed herein wherein A₂ is present—represents C—H and where T—in formula (IV) and all further formulae disclosed herein wherein T is present—represents T3, T8 or T9, and Q in all formulae disclosed herein wherein Q is present represents optionally with cyano substituted C₃-C₆-cycloalkyl or C₆-aryl-C₁-C₃-alkyl.

Another preferred embodiment refers to a process for the preparation of compound IV where R¹ in all formulae disclosed herein wherein R¹ is present—represents methyl and T—in all formulae disclosed herein wherein T is present—represents T3, T8 or T9 and n—in all formulae disclosed herein wherein n is present—represents 0 and A₁—in all formulae disclosed herein wherein A₁ is present—represents C—Cl and A₂—in all formulae disclosed herein wherein A₂ is present—represents C—H and Q—in all formulae disclosed herein wherein Q is present—represents with cyano substituted cyclopropyl (e.g. 1-cyano-cyclopropyl) or benzyl.

Another aspect of the present invention refers to a process for the preparation of compound (II) comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

One aspect of the present invention refers to a process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIa), comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

In a preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIa) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 5 and 6 as described in paragraphs [0104] to [0117].

In another preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIa) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 5 and 6 as described in paragraphs [0104] to [0117] and step 8 as described in paragraphs [0124] to [0147].

In another preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIa) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 5 and 6 as described in paragraphs [0104] to [0117] and step 8 as described in paragraphs [0124] to [0147], wherein the reaction of Step 8 is carried out in the absence of an acid acceptor.

Another aspect of the present invention refers to a process for the preparation of compound (III) comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

Another aspect of the present invention refers to a process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIIa), comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

In a preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIIa) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 9 and 10 as described in paragraphs [0152] to [0157].

Another aspect of the present invention refers to a process for the preparation of compound (III″) comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

Another aspect of the present invention refers to a process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIIb) comprising steps 1 to 4 as described in paragraphs [0063] to [0103].

In a preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIIb) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 9 and 10 as described in paragraphs [0152] to [0157].

In a preferred embodiment, the process for the preparation of compound (IV) where a compound of formula (IV) is compound (IIIb) comprises steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 11 and 12 as described in paragraphs [0161] to [0171].

The present invention also refers to a process for the preparation of a compound of formula (6), preferably of formula (6a), comprising the steps 1 to 4 as described in paragraphs [0063] to [0103].

The present invention also refers to a process for the preparation of a compound of formula (6), preferably of formula (6a), comprising the steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 5 and 6 as described in paragraphs [0104] to [0117].

The present invention also refers to a process for the preparation of a compound of formula (7), preferably of formula (7a), comprising the steps 1 to 4 as described in paragraphs [0063] to [0103].

The present invention also refers to a process for the preparation of a compound of formula (7), preferably of formula (7a), comprising the steps 1 to 4 as described in paragraphs [0063] to [0103] and steps 5 and 6 as described in paragraphs [0104] to [0117].

The present invention also refers to a process for the preparation of a compound (I), (II), (III) or (IV), wherein Step 3 and Step 4 are carried out in the same solvent, preferably acetonitrile or methylene chloride, more preferably methylene chloride.

The present invention also refers to a process for the preparation of a compound (I), (II), (III) or (IV), wherein Step 3 and Step 4 are carried out as a one-pot reaction in the same solvent, preferably acetonitrile or methylene chloride, more preferably methylene chloride.

The present invention also refers to a process for the preparation of a compound (I), (II), (III) or (IV), wherein Step 2, Step 3 and Step 4 are carried out in the same solvent.

The present invention also refers to a process for the preparation of a compound (I), (II), (III) or (IV), wherein Step 2, Step 3 and Step 4 are carried out as a one-pot reaction in the same solvent.

In one aspect, the present invention also refers to the use of compounds of formula (1) to prepare a compound of formula (I), preferably of formula (Ia).

In one aspect, the present invention also refers to the use of compounds of formula (1) to prepare a compound of formula (II), preferably of formula (IIa).

Moreover, the present invention also refers to the use of compounds of formula (1) to prepare a compound of formula (III), preferably of formula (III′), more preferably of formula (IIIa).

Moreover, the present invention also refers to the use of compounds of formula (1) to prepare a compound of formula (III″), preferably of formula (III″′), more preferably of formula (IIIb).

Moreover, the present invention also refers to the use of compounds of formula (1) to prepare a compound of formula (IV), preferably of formula (IV′).

Example 1 (Step 1) Preparation of Perfluoro-2-methyl-4-pentene (intermediate (2)

Into a suspension of 5 g CsF in 100 ml acetonitrile (CH₃CN) 300 g of hexafluoropropen (HFP) were slowly introduced to keep the temperature in reactor below 30° C. After introduction of HFP the mixture was heated for 8 h at 50-55° C. and cooled to 10° C. The bottom layer was separated and distilled at yielding 260 g of Perfluoro-2-methyl-4-pentene. Yield 87%. B.p. 50° C.

Example 2 (Step 2) Preparation of Perfluoro-2-methyl-2-pentene (intermediate (3)

Perfluoro-2-methyl-4-pentene 210 g and 1 g of dry CsF in 300 ml CH₃CN were heated for 8 h at 50-55° C. The mixture was cooled to 5-10° C. and phases were separated. The bottom phase 195 g (93%) (pure perfluoro-2-methyl-2-pentene) was used without purification for the preparation of perfluoro-2-methyl-2-penten-)-3-triethylammonium-enolate according to example 3.

Example 3 (Step 3) Enolate Preparation in CH₃CN According to Martini et al. (1976) Preparation of (Perfluoro-2-methyl-2-penten-)3-triethylammonium-enolate (intermediate (4)

In a 3-kneck flask equipped with condenser, thermometer and a dropping funnel 1300 ml CH₃CN and perfluoro-2-methyl-2-pentene (196 g, 0.65 mol) was placed and then 12 g water were added. The mixture was cooled to 0° C. and Et₃N (164 g, 1.6 mol) was added at a temperature ranging from 0° C. to 5° C.

The mixture was stirred 1 h at 10° C. Yield based on ¹⁹F NMR data against reference: 76-78%. The solution was used for the next step without isolation.

Example 4 (Step 4 Starting from Enolate in CH₂Cl₂) Preparation of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole (compound (Ia)) starting from isolated enolate in CH₂Cl₂

In a 3-kneck flask equipped with condenser, thermometer, and a dropping funnel 100 ml methylene chloride and (perfluoro-2-methyl-2-penten-)3-triethylammonium-enolate (25.9 g, 0.065 mol) was placed, and then a 40% solution of N-methylhydrazine in water (8 g) was slowly added to this mixture at 0° C. The reaction mixture was stirred for 1 h at 5° C., and finally for 2 h at 20° C. The mixture was washed with water (3×50 ml), the organic layer was dried over Na₂SO₄ and the solvent was distilled off under atmospheric pressure. The crude product was purified via vacuum distillation. The yield of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole was 15, 8 g. (yield: 85% based on perfluoro-2-methyl-2-pentene) boiling point 62-65° C. at 17 mbar.

¹⁹F NMR δ: 53.7 (3F), 83.9 (3F), 112.1 (2F), 125.1 (1F) ppm.

Example 5 (Step 3+Step 4, One-Pot Reaction) Preparation of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole (compound (Ia)) starting from perfluoro-2-methyl-2-pentene in CH₂Cl₂

In a 3-kneck flask equipped with condenser, thermometer, and a dropping funnel 1300 ml methylene chloride and perfluoro-2-methyl-2-pentene (196 g, 0.65 mol) was placed and then 12 g water were added. The mixture was cooled to 0° C. and Et₃N (164 g, 1.6 mol) was added at a temperature ranging from 0° C. to 5° C. The mixture was stirred at this temperature for 15-30 min and 40% solution of methylhydrazine in water (80 g) was slowly added to this mixture at 0° C. The reaction mixture was stirred for 1 h at 5° C. and finally for 8 h at 20° C. The mixture was washed with water (3×150 ml), the organic layer was dried over Na₂SO₄ and the solvent was distilled off under atmospheric pressure. The crude product was purified via vacuum distillation. The yield of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole was 150 g. (yield: 81% perfluoro-2-methyl-2-pentene) (boiling point 62-65° C. at 17 mbar).

¹⁹F NMR δ: 53.7 (3F), 83.9 (3F), 112.1 (2F), 125.1 (1F) ppm.

Example 6 (Step 2+Step 3+Step 4 One Pot Reaction in CH₃CN Preparation of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole (compound (Ia))

Perfluoro-2-methyl-4-pentene (196 g. 0.65 mol) and 2 g of dry CsF in 1300 ml CH₃CN were heated for 8 h at 50-55° C. The mixture was cooled to 10° C. and then 15 g water were added. The mixture was cooled to 0° C. and Et₃N (164 g, 1.6 mol) was added at a temperature ranging from 0° C. to 5° C. The mixture was stirred at this temperature for 15-30 min and 40% solution of N-methylhydrazine in water (80 g) was slowly added to this mixture at 0° C. The reaction mixture was stirred for 1 h at 5° C. and finally for 12 h at 20° C. The solvent was removed in vacuum (500 mbar) and oily product was dissolved in 400 ml MTBE. Organic solution was washed with water (3×150 ml), dried over Na₂SO₄ and the solvent was distilled off under atmospheric pressure. The crude product was purified via vacuum distillation. The yield of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole was 139 g. (74%) (boiling point 62-65° C. at 17 mbar).

¹⁹F NMR δ: 53.7 (3F), 83.9 (3F), 112.1 (2F), 125.1 (1F) ppm.

Example 7 (Step 5) Preparation of 5-Cyano-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole (intermediate (6a))

28.6 g (0.1 mol) of 5-fluoro-1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole (compound (Ia)) and 9.7 g (0.15 mol) of potassium cyanide are suspended in 150 ml of acetonitrile and then heated under reflux for 5 h under a protective gas atmosphere. After cooling, the precipitate (KCN, KF) was filtered off, and the solvent was removed in vacuo 300 mbar to give a brawn oil (27.8 g, 95%) which was used for further step without any purification.

¹H-NMR (400 MHz, d₃-acetonitrile): δ=4.11 (s, 3H, CH₃) ppm

¹⁹F-NMR (400 MHz, CDCl₃): δ=−56.7 (3F), −111.4 (3F), −111.6 (2F) ppm.

GC-MS: Retention time 2.67 min; mass (m/z): 224 (M)⁺.

Example 8 (Step 6) Preparation of 1-Methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole-5-carboxylic acid (intermediate (7a))

29.3 g (0.1 M) of 5-cyano-1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole (compound (6a)) and 110 g of 10% NaOH were heated in an oil bath at 100° C. for 6 h until clear solution formed. After cooling to 5° C., the reaction mixture was slowly acidify to pH 1 by adding of 37% HCl to give a white crystals which were filtered off, washed with 40 ml cold water and dried yielding 28 g (7a) of 1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole-5-carboxylic acid) as a white solid with m.p. 120-122° C.

¹H-NMR (400 MHz, d₃-acetonitrile) 6=4.08 (s, 3H, CH₃) ppm;

HPLC-MS^(a)): log P=1.86; mass (m/z): 313.0 (M+H)⁺. ¹ The stated mass is the peak of the isotope pattern of the [M+H]⁺ ion with the highest intensity.^(a)) Note regarding the determination of the log P values and mass detection: The log P values given were determined in accordance with EEC Directive 79/831 Annex V.A8 by HPLC (High Performance Liquid Chromatography) on a phase inversion column (C18). Agilent 1100 LC system; 50*4.6 Zorbax Eclipse Plus C18 1.8 micron; eluent A: acetonitrile (0.1% formic acid); eluent B: water (0.09% formic acid); linear gradient from 10% acetonitrile to 95% acetonitrile in 4.25 min, then 95% acetonitrile for a further 1.25 min; oven temperature 55° C.; flow: 2.0 ml/min. The mass detection is carried out via an Agilend MSD system.

Example 9 (step 9) Preparation of 4-bromo-2′-methyl-5′-(pentafluoroethyl)-4′-(trifluoromethyl)-2′H-1,3′-bipyrazole (intermediate (12))

2.00 g (6.99 mmol) of 5-fluoro-1-methyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole (compound (Ia)), 1.03 g (6.99 mmol) of 4-bromo-1H-pyrazole (compound of formula (11)) and 1.93 g of potassium carbonate are suspended in 50 ml of tetrahydrofuran p.a. The reaction mixture is heated under reflux for 16 h. The cooled reaction mixture is filtered and the solvent is removed under reduced pressure. The residue is purified by column chromatography on silica gel.

This gives 0.69 g of 4-bromo-2′-methyl-5′-(pentafluoroethyl)-4′-(trifluoromethyl)-2′H-1,3′-bipyrazole as a colourless solid.

¹H-NMR (400 MHz, d₃-acetonitrile): 6=8.00 (s, 1H), 7.91 (s, 1H), 3.71 (s, 3H).

HPLC-MS^(a)): log P=4.14, mass (m/z)=413 [M+H]⁺.

Example 10 (step 10) Preparation of 2-Chloro-N-1-cyano-cyclopropyl-5-[2′-methyl-5′-(pentafluoroethyl)-4′-(trifluoromethyl)-2′H-1,3′-bipyrazol-4-yl]benzamide (compound (IIIa))

150 mg (0.36 mmol) 4-bromo-2′-methyl-5′-(pentafluoroethyl)-4′-(trifluoromethyl)-2′H-1,3′-bipyrazole, 126 mg (0.36 mmol) 2-chloro-N-(1-cyanocyclopropyl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)benzamide, 21 mg (0.01 mmol) tetrakis(triphenylphosphin)palladium and 1.1 ml of 1M aqueous sodium bicarbonate were mixed with 10.5 ml isopropanol and heated under reflux for 3 h. The solvent is removed under reduced pressure and the residue is dissolved in ethylacetat. The organic phase was washed two times with water, dried over Na₂SO₄, and filtered. The solvent is removed under reduced pressure. The residue was purified vie column chromatography with silica gel, yielding 98 mg 2-chloro-N-(1-cyanocyclopropyl)-5-[2′-methyl-5′-(pentafluoroethyl)-4′-(trifluoromethyl)-2′H-1,3′-bipyrazole-4-yl]benzamide as colorless solid.

¹H-NMR (400 MHz, d₃-Acetonitril): δ=¹H-NMR (400 MHz, d3-Acetonitril): δ=8.27 (s, 1H), 8.25 (s, 1H), 7.75 (d, 1H), 7.70 (dd, 1H), 7.62 (s, 1H), 7.51 (d, 1H), 3.75 (s, 3H), 1.56-1.60 (m, 2H), 1.33-1.36 (m, 2H).

HPLC-MS^(a)): log P=3.72, Masse (m/z)=553.1 [M+H]⁺.

Example 11 (step 11) Preparation of 5-Azido-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole (intermediate (VI) according to WO 2012 107434

5-Fluoro-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole (prepared according to steps 1 to 4; 7 mmol) is added to a mixture of dimethyl sulfoxide (DMSO) (10 ml). Sodium azide (0.5 g; 7.7 mmol) is then added into the mixture, which is kept at room temperature. The mixture is stirred overnight at RT. After the reaction is complete, a mixture of water (100 mL) and diethyl ether (100 mL) is added. The phases are separated and the aqueous phase extracted twice with diethyl ether. This compound is used without extra purification.

Example 12 (step 12) Preparation of 2-Chloro-5-[1-(2-methyl-5-pentafluoroethyl-4-trifluoromethyl-2H-pyrazol-3-yl)-1H[1,2,3]triazol-4-yl]-benzoic acid methyl ester (compound of formula (VIII)) according to WO 2012 107434

2-Chloro-5-ethynyl-benzoic acid methyl ester (1.13 g, 5.8 mmol) and 5-Azido-1-methyl-3-pentafluoroethyl-4-trifluoromethyl-1H-pyrazole (1.80 g, 5.8 mmol) is suspended in a mixture of water and t-BuOH (30 ml). Sodium ascorbate (0.600 ml 1 M sol. in water, freshly prepared) is added to the mixture followed by copper (II) sulfate pentahydrate (0.015 g). The resulting heterogeneous mixture is stirred vigorously for 96 hours. The reaction mixture is diluted with water and the product extracted with ethyl acetate. The organic phase is washed with brine, dried over magnesium sulphate and evaporated. The resisue is subjected to silica gel column chromatography (c-HEX/EtOAc=3:1) affording the desired product 2-Chloro-5-[1-(2-methyl-5-pentafluoroethyl-4-trifluoromethyl-2H-pyrazol-3-yl)-1H-[1,2,3]triazol-4-yl]-benzoic acid methyl ester (yield 53%).

¹H-NMR (400 MHz, CDCl₃): δ=8.47 (s, 1H), 8.12 (Is, 1H), 8.0 (d, 1H), 7.62 (d, 1H), 3.98 (s, 3H), 3.87 (s, 3H) ppm.

LC-MS RT 2.12, 504 (M+H+), 545 (M+CH₃CN+H⁺)

Example 13 (step 13) Preparation of 2-Chloro-5-[1-(2-methyl-5-pentafluoroethyl-4-trifluoromethyl-2H-pyrazol-3-yl)-1H[L2,3]triazol-4-yl]-benzoic acid (compound of formula (IX))

2-Chloro-5-[1-(2-methyl-5-pentafluoroethyl-4-trifluoromethyl-2H-pyrazol-3-yl)-H-[1,2,3]triazol-4-yl]-benzoic acid methyl ester (1.53 g, 3.0 mmol) is suspended in a mixture of water and tetrahydrofuran (1:3, 50 mL) and lithium hydroxide (0.22 g, 9.1 mmol) is added. The resulting mixture is stirred vigorously for 5 hours at 60° C. The reaction mixture is diluted with water and acidified with hydrogen chloride (2N). The aqueous phase is extracted twice with AcOEt, dried over MgSO₄ and concentrated under vacuum to afford the desired product 2-Chloro-5-[1-(2-methyl-5-pentafluoroethyl-4-trifluoromethyl-2H-pyrazol-3-yl)-1H-[1,2,3]triazol-4-yl]-benzoic acid. This compound was used without extra purification.

¹H-NMR (400 MHz, CDCl₃): δ=8.52 (s, 1H), 8.18 (Is, 1H), 8.09 (d, 1H), 7.66 (d, 1H), 3.88 (s, 3H) ppm.

LC-MS RT 2.08, 488 (M+H+).

Example 14 (step 8) Preparation of N-[4-chloro-3-(benzylcarbamoyl)phenyl]-1-methyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carboxamide (compound (IIa)) according to WO 2010/051926

560 mg (1.79 mmol) of 1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole-5-carboxylic acid were suspended in 10 ml of dichloromethane. The suspension was cooled to 0° C. and then subsequently admixed with 0.02 ml of N,N-dimethylformamide and 188 μl (2.15 mmol; 1.2 eq) oxalyl chloride. The reaction mixture was stirred firstly for 0.5 h at 0° C. and then for 3 hours at room temperature. The solvent was removed under reduced pressure on a rotary evaporator. The resulting 1-methyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carbonyl chloride was used for the subsequent synthesis step without further work-up.

88.7 mg (0.34 mmol) of 5-amino-N-benzyl-2-chlorobenzamide, 2.77 mg (0.02 mmol) of N,N-dimethylpyridine-4-amine (DMPA) are dissolved in 2.5 ml of ethyl acetate. The solution is cooled to 0° C. using an ice bath and admixed with 119 μl (0.68 mmol) of N-ethyldiisopropylamine. 75.0 mg (0.22 mmol) of 1-methyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carbonyl chloride are suspended in 2.5 ml of ethyl acetate and then added to the cooled reaction solution. The reaction mixture is heated for four hours at 50° C. and then stirred for 16 hours at room temperature. The reaction solution is diluted with 10.0 ml of ethyl acetate. The organic phase is washed three times with 1M hydrochloric acid, twice with 1M sodium hydroxide solution and once with saturated sodium chloride solution. The organic phase is dried over sodium sulphate and filtered and solvent is removed under reduced pressure on a rotary evaporator. This gives 140 mg (0.17 mmol) of N-[4-chloro-3-(benzylcarbamoyl)phenyl]-1-methyl-3-(pentafluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carboxamide (97%) as white solid.

¹H-NMR (400 MHz, d₃-acetonitrile): δ=9.29 (bs, 1H), 7.78 (d, 1H), 7.67 (dd, 1H), 7.48 (d, 1H), 7.21-7.52 (m, 6H), 4.54 (d, 2H), 3.97 (s, 3H) ppm.

HPLC-MS^(a)): log P=3.90 mass (m/z)=555.1 [M+H]⁺. 

The invention claimed is:
 1. A process for synthesis of 5-fluoro-1H-pyrazoles of formula (I)

wherein R¹ represents optionally halogenated (C₁-C₄)alkyl or optionally halogenated cyclopropyl; comprising preparing perfluoro-4-methyl-2-pentene (intermediate (2)) in a Step 1

by reacting hexafluoropropene (compound (1))

in the presence of a catalyst to form its dimer perfluoro-4-methyl-2-pentene; and preparing perfluoro-2-methyl-2-pentene (intermediate (3)) in a Step 2

by isomerizing perfluoro-4-methyl-2-pentene into perfluoro-2-methyl-2-pentene; and preparing perfluoro-2-methyl-2-penten-)3-enolate (intermediate (4)) in a Step 3

wherein Cat⁺ refers to a positively charged organic ion, alkaline metal cation or alkaline earth metal cation, by reacting perfluoro-2-methyl-2-pentene with water and a base; and preparing compound of formula (I) in a Step 4 by reacting intermediate (4) in Step 4 with a hydrazine of formula (5) R1-NH—NH₂   (5) wherein R¹ is optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl.
 2. A process for preparation of a compound of formula (IV)

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl; A₁ is C—R²; R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy, optionally halogenated C₁-C₄-alkylsulphonyl, optionally halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl (—C(═O)—NH—cyclopropyl); methyl, ethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy, difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, 2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl, methylsulphinyl, trifluoromethylsulphonyl, trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl; A₂ is C—R³ or nitrogen; R³ is hydrogen, methyl, fluorine or chlorine; T represents one of T1-T9 listed below, where the bond to the pyrazole head group is marked with an asterisk *,

R⁶ independently of one another represents halogen, cyano, nitro, amino or optionally substituted C₁-C₆-alkyl, C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl, C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl; n represents 0-2, provided that n is 0 or 1 in T5, T6 and T8 and provided n is 0 in T7; Q is hydrogen, cyano, hydroxy, formyl, C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl, C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl, C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl, C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl, aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which are optionally substituted with one, two, three, four or five, substituents independently selected from the group consisting of hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano, hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl, C₄-C₆-cycloalkylcarbamoyl and optionally independently with one, two or three substituents selected from the group consisting of halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl, C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted phenyl; comprising steps 1, 2, 3 and 4 of the process as described in claim
 1. 3. A process according to claim 2, wherein a compound of formula (IV) is a compound of formula (II),


4. A process according to claim 2, wherein a compound of formula (IV) is compound (IIa)


5. A process according to claim 2, further comprising: reacting in a Step 5 compound (I) with a cyano-donor to prepare intermediate of formula (6)

wherein R¹ is optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl; and reacting in a Step 6 compound (6) with an inorganic strong base in a first hydrolysis step followed by adding an inorganic acid in a second hydrolysis step to prepare intermediate of formula (7)

wherein R¹ is optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl; and reacting in a Step 8 a compound of formula (8) or its salt (8′) with an activated form (7′) of compound (7)

wherein LG is any leaving group, to prepare a compound of formula (II).
 6. A process according to claim 2, wherein a compound of formula (IV) is a compound of formula (III)

wherein R¹ is hydrogen, optionally halogenated C₁-C₄-alkyl or optionally halogenated cyclopropyl; A₁ is C—R²; R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, optionally halogenated C₁-C₆-alkyl, optionally halogenated C₁-C₄-alkoxy, optionally halogenated C₁-C₄-alkylsulphonyl, optionally halogenated C₁-C₄-alkylsulphinyl or N-cyclopropylaminocarbonyl (—C(═O)—NH—cyclopropyl); methyl, ethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, n-propoxy, 1-methylethoxy, fluoromethoxy, difluoromethoxy, chlorodifluoromethoxy, dichlorofluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, 2-chloro-2,2-difluoroethoxy, pentafluoroethoxy, methylsulphonyl, methylsulphinyl, trifluoromethylsulphonyl, trifluoromethylsulphinyl or N-cyclopropylaminocarbonyl; A₂ is C—R³ or nitrogen; R³ is hydrogen, methyl, fluorine or chlorine; Q is hydrogen, cyano, hydroxy, formyl or one of the groupings C₁-C₆-alkyl, C₃-C₆-alkenyl, C₃-C₆-alkynyl, C₃-C₉-cycloalkyl, C₃-C₉-heterocycloalkyl, C₁-C₄-alkoxy, C₄-C₁₅-alkylcycloalkyl, C₄-C₁₅-cycloalkylalkyl, C₁-C₆-hydroxyalkyl, C₆-aryl-C₁-C₃-alkyl, C₅-C₆-heteroaryl-C₁-C₃-alkyl, C₁-C₄-aminoalkyl, aminocarbonyl-C₁-C₄-alkyl or C₁-C₄-alkyl-amino-C₁-C₄-alkyl which are optionally substituted with one, two, three, four or five, substituents independently selected from the group consisting of hydroxy, nitro, amino, halogen, C₁-C₃-alkoxy, cyano, hydroxycarbonyl, C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylcarbamoyl, C₄-C₆-cycloalkylcarbamoyl and optionally independently with one, two or three substituents selected from the group consisting of halogen, cyano, nitro, hydroxycarbonyl, C₁-C₂-alkylcarbamoyl, C₁-C₂-alkyl, C₁-C₂-haloalkyl and C₁-C₂-alkoxy substituted phenyl; T represents one of 5-membered heteroaromatics T1-T8 listed below, where the bond to the pyrazole head group is marked with an asterisk *,

wherein R⁶ independently of one another represents halogen, cyano, nitro, amino or optionally substituted C₁-C₆-alkyl, C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl, C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and n represents 0-2, provided that n is 0 or 1 in T5, T6 and T8 and provided n is 0 in T7.
 7. A process according to claim 6, wherein a compound of formula (III) is compound of formula (III′)


8. A process according to claim 6, comprising said Steps 1 to 4 and further comprising reacting a compound of formula (I) with an intermediate of formula (11) by nucleophilic substitution of the fluoride at the ring position of a compound of formula (I) (herein referred to as Step 9)

wherein R¹ is optionally halogenated (C₁-C₄)alkyl or optionally halogenated cyclopropyl; U represents bromine, iodine, triflate, boronic acid, boronic ester or trifluoroboronate; five-membered cycles of E₁-E₃, carbon and nitrogen represent 5-membered heterocycles selected from the group consisting of

wherein R⁶ independently of one another represents halogen, cyano, nitro, amino or optionally substituted C₁-C₆-alkyl, C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl, C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, and n represents 0-2, provided that n is 0 or 1 in T5, T6 and T8 and provided n is 0 in T7; to prepare an intermediate of formula (12); and reacting a compound of formula (12) and a compound of formula (13) (herein referred to as Step 10)

wherein R¹, A₁, A₂, and Q are as defined for a compound of formula (III) and U represents bromine, iodine, triflate, boronic acid, boronic ester or trifluoroboronate; and five-membered cycles of E₁-E₃, carbon and nitrogen represent 5-membered heterocycles selected from the group consisting of

wherein R⁶ independently of one another represents halogen, cyano, nitro, amino or optionally substituted C₁-C₆-alkyl, C₁-C₆-alkyloxy, C₁-C₆-alkylcarbonyl, C₁-C₆-alkylsulphanyl, C₁-C₆-alkylsulphinyl, C₁-C₆-alkylsulphonyl, n represents 0-2, provided that n is 0 or 1 in T5, T6 and T8 and provided n is 0 in T7; and M represents bromine, iodine or triflate when U represents a boronic acid, boronic ester or trifluoroboronate; or M represents a boronic acid, boronic ester or trifluoroboronate when U represents bromine, iodine or triflate to prepare a compound of formula (III).
 9. A process according to claim 2, wherein a compound of formula (IV) is a compound of formula (III″)


10. A process according to claim 9, comprising said steps 1 to 4, either optionally further comprising steps 9 and 10; or optionally further comprising reacting a compound of formula (I) and an azide-donor to prepare intermediate (14) (herein referred to as Step 11)

wherein R¹ is as defined for a compound of formula (III); and reacting intermediate (14) with an intermediate of formula (15) to give an intermediate (III″*) (herein referred to as Step 12)

wherein R¹, R⁶, A₁, and A₂ are as defined for compound (III), n is 0 or 1 and PG is any protective group of the carboxylic group such as C₁-C₆-alkyl.
 11. A process according to claim 1, wherein R¹ is methyl.
 12. A process according to claim 1, wherein the catalyst in Step 1 and the fluoride donor in Step 2 are identical.
 13. A process according to claim 1, wherein a solvent in Step 3 and Step 4 is identical.
 14. The process according to claim 3, wherein the compound of formula (II) is a compound of formula (II′),


15. The process according to claim 7, wherein the compound of formula (III′) is a compound of formula (IIIa),

or a compound of formula (IIIb),


16. The process according to claim 9, wherein the compound of formula (III″) is a compound of formula (III′″),


17. The process according to claim 2, wherein R² is hydrogen, fluorine, chlorine, bromine, CN, NO₂, methyl, fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, or pentafluoroethoxy; Q is C₃-C₆-cycloalkyl, or C₃-C₆-cycloalkyl which is substituted with at least one substituent selected from the group consisting of chlorine, fluorine, bromine, iodine, cyano and hydroxy, or C₆-aryl-C₁-C₃-alkyl. 